Author: baiyuzhan

I. Introduction

In the realm of industrial automation, the stability of servo systems is the cornerstone of machining precision and production efficiency. The ZSMC K-Series (Zhejiang Zhishan Electric Co., Ltd.), a leading domestic servo system in China, is widely deployed in CNC machine tools, robotics, packaging machinery, and textile equipment. Its core competitive advantage lies in its support for bus-type absolute encoders, enabling high-precision position control and multi-turn position memory without the need for homing sequences upon every power-up.

However, Alarm 27 (Bus Encoder Battery Alarm 1) is one of the most frequent and critical faults encountered in this series. If not addressed promptly, it can lead to production downtime, positional deviations, and even mechanical collisions. This article provides a comprehensive technical analysis of Alarm 27, covering its definition, root causes, operational impact, step-by-step troubleshooting, and preventive maintenance strategies. This guide is designed to serve as a practical reference for field engineers and maintenance personnel.

II. Technical Definition and Trigger Mechanism of Alarm 27

1. Fault Definition

According to the official ZSMC K-Series manual, Alarm 27 corresponds to “Bus Encoder Battery Alarm 1”. The specific technical parameters are:

• Trigger Condition: The built-in battery voltage of the encoder drops below 2.5V (the critical threshold).
• Associated Phenomenon: Loss of Multi-turn Position Information (the total count of motor rotations).
• Drive Action: The drive enters a protection state, inhibiting motor operation. The digital panel displays “27” or a specific battery warning code.

2. Working Principle of Bus-Type Absolute Encoders

Unlike incremental encoders, bus-type absolute encoders (utilizing protocols such as RS485 or CANopen) transmit absolute position data via a serial bus to the drive. This data includes:

• Single-turn Position: The angular position within one revolution (0–360°).
• Multi-turn Position: The cumulative count of revolutions since power-on.

The “absolute” nature means the system knows its exact position immediately upon power-up. This capability relies entirely on a backup power source to maintain the counter in non-volatile memory (NVRAM) or specific registers during power outages.

3. Core Function of the Encoder Battery

The encoder typically uses a CR2032 lithium coin cell (nominal voltage 3.0V) for the following purposes:

• Maintaining Multi-turn Counters: Preserving the count of total motor rotations.
• Storing Parameters: Saving encoder-specific data (resolution, zero offset, communication baud rate).
• Powering Static Logic: Supplying the minimal current required for the memory retention circuit.

When the voltage falls below 2.5V, the NVRAM can no longer retain data reliably. Consequently, the multi-turn count resets to zero or becomes invalid, triggering Alarm 27 to prevent the drive from operating with unknown position data.

III. Deep-Dive Root Cause Analysis

While the symptom is “low battery,” the underlying causes are multifaceted. We categorize them into four dimensions: Battery Integrity, Installation/Connection, Component Compatibility, and Environmental Factors.

1. Battery-Specific Factors

• Natural Lifecycle: A standard CR2032 battery has a lifespan of 3–5 years at 25°C. However, in high-load applications where the encoder communicates frequently via the bus, the discharge rate increases, potentially shortening lifespan to 1–2 years.
• Quality Issues: Counterfeit or low-quality batteries often have unstable voltage outputs or lower actual capacity. For instance, a factory using generic brand batteries reported Alarm 27 triggering within 6 months of installation.
• Incorrect Specification: Using a battery with insufficient capacity (e.g., CR2025 instead of CR2032) results in rapid voltage sag under load.

2. Installation and Connection Issues

• Contact Resistance: Oxidation on battery terminals (copper oxide/verdigris) or loss of spring tension in the battery holder creates high contact resistance. This causes a “voltage drop” where the actual battery voltage might be 2.8V, but the drive detects only 2.3V due to resistance.
• Polarity Reversal: Installing the battery backward (positive to negative) can cause immediate short circuits or prevent the circuit from charging/discharging correctly.
• Loose Bus Cabling: A loose connector on the encoder bus cable (e.g., RS485 A/B lines) can cause communication timeouts. Some ZSMC drives interpret communication failures as battery faults as a fail-safe mechanism.

3. Encoder and Drive Hardware Faults

• Encoder Internal Short Circuit: Corrosion inside the encoder battery compartment or a failed capacitor on the encoder PCB can create a parasitic drain, draining the battery in weeks rather than years.
• Drive Detection Circuit Failure: The voltage divider resistors or ADC (Analog-to-Digital Converter) chip on the drive’s control board may fail. In this scenario, the battery is fine, but the drive “hallucinates” a low voltage.
• Protocol Mismatch: If the encoder uses CANopen but the drive is configured for RS485 (or vice versa), the handshake fails. While this usually triggers a communication alarm (e.g., Alarm 28), it can sometimes cascade into Alarm 27 if the drive cannot read the battery status register.

4. Environmental Factors

• High Temperature: Lithium batteries degrade rapidly above 60°C. The chemical reaction rate doubles for every 10°C increase (Arrhenius equation). In a forging workshop where ambient temperatures reach 70°C, battery life can shrink to less than 12 months.
• High Humidity: Humidity >80% causes galvanic corrosion on battery contacts, increasing resistance and leading to intermittent voltage detection errors.
• Electromagnetic Interference (EMI): Proximity to high-power inverters or welders can induce noise on the encoder cables. This noise can corrupt the serial data stream, causing the drive to misinterpret the battery voltage telemetry.

IV. Impact Assessment of Alarm 27

Ignoring Alarm 27 poses significant risks to production and equipment integrity:

1. Operational Impact

• Hard Lockout: The servo cannot start. In a CNC lathe, this means the spindle cannot turn, halting the entire production line.
• Homing Failure: After battery replacement, if the multi-turn data is lost, the machine must re-home. If the homing method (e.g., external limit switch) is misconfigured, the axis may drift or fail to find zero.
• Position Deviation: If the operator forces the motor to run in “relative mode” without multi-turn data, the position feedback will be inaccurate. For example, a robot arm might think it has rotated 10 times when it has only rotated 5, leading to collision or scrap parts.

2. Production and Economic Impact

• Downtime Costs: For an automotive production line, one hour of downtime can cost tens of thousands of dollars in lost output.
• Scrap Rates: Position errors lead to out-of-tolerance parts. In precision machining (±0.01mm), a lost multi-turn count can result in 100% scrap rates for a batch.
• Mechanical Damage: Running a servo without absolute position knowledge can cause the tool post to crash into the chuck or the robot arm to exceed soft limits, damaging gearboxes and ball screws.

3. Long-Term Equipment Health

• Battery Leakage: If a lithium battery is discharged below 2.0V, it risks leaking electrolyte, which corrodes the encoder PCB, permanently destroying the encoder.
• Drive Stress: Repeated power cycles while the alarm is active can stress the drive’s IGBT modules and DC bus capacitors.

V. Troubleshooting and Resolution Procedures

(一) Systematic Troubleshooting Flow

Step 1: Confirm the Alarm Code

• Verify via the drive’s 7-segment LED display or the ZSMC Studio software that the code is specifically “27” (Bus Encoder Battery Alarm).
• Note: Check for coupled alarms. If Alarm 28 (Communication Error) is present, address the cabling first.

Step 2: Measure Battery Voltage

1. Disconnect main power to the drive (wait 5 minutes for capacitors to discharge).
2. Open the encoder battery cover (usually located on the rear or side of the motor).
3. Use a multimeter (DC Voltage mode) to measure across the battery terminals:
   • ≥ 2.8V: Battery is healthy; investigate connection or drive logic.
   • 2.5V – 2.8V: Battery is nearing end-of-life; schedule replacement.
   • < 2.5V: Battery is dead; immediate replacement required.

Step 3: Inspect Physical Connections

• Battery Holder: Check spring tension. Clean oxidized terminals with isopropyl alcohol and a fiberglass pen.
• Bus Cable: Unplug and re-plug the encoder cable. Ensure the shielding is grounded properly. Check for pinched wires or broken conductors.
• Mounting: Verify the encoder coupling set screw is tight (Torque: 5–8 N·m for ZSMC K-series).

Step 4: Verify Compatibility via Software

• Connect to ZSMC Studio (or the handheld debugger).
• Read Encoder Information: Confirm the model matches the drive configuration (e.g., “ZSMC-E-2048-4-24V”).
• Check Protocol Settings: Ensure Pn001 (Encoder Type) is set to “Bus Absolute Encoder” (not “Incremental” or “Sin-Cos”).

Step 5: Isolate the Faulty Component

• Swap Test: Replace the battery. If the alarm persists, swap the encoder with a known-good spare.
  • Alarm disappears: Original encoder is faulty (internal circuit failure).
  • Alarm remains: The drive’s detection circuit is likely damaged (requires board-level repair or drive replacement).

(二) Detailed Resolution Operations

1. Replacing the Encoder Battery

Tools: Multimeter, Phillips screwdriver, CR2032 battery (Genuine ZSMC or reputable brand like Panasonic/Sony).
Procedure:

1. Power Down: Cut main power and wait 5 minutes.
2. Access: Remove the encoder cover. Extract the old battery (avoid touching the PCB).
3. Install: Insert the new battery with correct polarity (+ to +).
4. Secure: Tighten the cover.
5. Power Up: Restore power.

Critical Note: While some encoders support hot-swapping, ZSMC K-series recommends power-off replacement to avoid bus contention. After replacement, use ZSMC Studio to perform a “Battery Learn” (Pn002 = 1) to recalibrate the drive’s voltage detection.

2. Restoring Multi-Turn Position (Homing)

Once the battery is replaced, the multi-turn count is lost. You must re-establish the mechanical zero. ZSMC K-series supports three methods:

• Method A: External Home (Recommended)
  1. Install a proximity sensor at the mechanical zero point.
  2. Set Pn003 (Homing Mode) = 2 (External Signal).
  3. Set Pn004 (Home Input Type) = 1 (NPN Normally Open).
  4. Press the “ORIGIN” button on the keypad. The motor will creep toward the sensor, stop upon detection, and set the position to 0.
• Method B: Z-Phase Home
  1. Use the encoder’s Z-pulse (once per revolution).
  2. Set Pn003 = 1.
  3. The drive finds the Z-pulse edge and sets it as zero. Note: This does not reset multi-turn count unless combined with a specific “Clear Multi-turn” command.
• Method C: Software/Manual Setting
  1. Connect ZSMC Studio.
  2. Manually rotate the axis to the mechanical zero.
  3. Click “Set Current Position as Zero” in the software.
  4. For multi-turn encoders, you may need to execute a “Multi-turn Clear” function (consult the specific encoder manual, e.g., ZSMC E-series “MULTI-TURN RESET”).

3. Addressing Environmental & Connection Issues

• Corrosion: Apply dielectric grease to battery terminals to prevent future oxidation.
• Vibration: Use cable ties to secure the bus cable to the motor body, preventing connector fatigue.
• Heat: Install a forced-air cooling fan (≥5 CFM) directed at the encoder, or maintain the servo cabinet temperature below 30°C using an air conditioner.
• Humidity: Place silica gel desiccants inside the cabinet or pot the encoder connector with epoxy for IP65 protection.

VI. Case Studies

Case 1: Intermittent Alarm Due to Poor Contact

Symptom: A ZSMC-K-110ST-M06025 servo on a CNC lathe triggered Alarm 27 intermittently. Replacing the battery did not fix it.
Investigation:

• Measured battery voltage: 2.9V (Good).
• Inspected holder: The positive spring was flattened and oxidized.
  Resolution:
• Bent the spring to restore tension.
• Cleaned contacts with contact cleaner.
• Result: Alarm cleared permanently.

Case 2: Premature Battery Failure in High Heat

Symptom: Robotic servos in a forging plant triggered Alarm 27 every 6 months (expected life: 3 years).
Investigation:

• Ambient temp near motor: 75°C.
• Battery voltage: 2.2V (Dead).
  Resolution:

1. Replaced batteries.
2. Installed aluminum heat sinks (100cm²) on the motor backs.
3. Installed an industrial air conditioner in the cabinet (set to 25°C).
   Result: Battery life extended to 2 years.

Case 3: Encoder Internal Short Circuit

Symptom: Packaging machine servo triggered Alarm 27 immediately after battery replacement. Could not home.
Investigation:

• ZSMC Studio read “Battery Voltage: 2.1V” despite new battery.
• Swapped encoder: Alarm cleared.
• Disassembled old encoder: Found corrosion on battery terminals and a shorted capacitor on the PCB (due to 85% humidity).
  Resolution:
• Replaced encoder.
• Installed industrial dehumidifier in the factory (humidity controlled to 60%).

VII. Preventive Maintenance & Strategy

1. Scheduled Battery Replacement

• Standard Environment (25°C): Check voltage every 12 months. Replace if < 2.8V.
• High Temp (>40°C): Check every 6 months.
• High Humidity (>70%): Check every 3 months.

2. Environmental Control

• Temperature: Maintain servo cabinet at 20–30°C.
• Humidity: Keep relative humidity at 40–60%.
• EMI: Use shielded twisted-pair cables for the bus. Ground the shield at the drive end only. Keep encoder cables 30cm away from power lines.

3. Component Standardization

• Batteries: Use only CR2032 from reputable sources (Panasonic, Sony, or ZSMC OEM).
• Encoders: Use ZSMC-approved absolute encoders (e.g., ZSMC E-series) to ensure protocol compatibility.
• Cables: Use factory-made bus cables (e.g., ZSMC-CABLE-RS485) to avoid impedance mismatch.

4. Digital Monitoring

• ZSMC Studio Alerts: Configure the software to trigger a “Pre-Alarm” when battery voltage drops to 2.8V, allowing maintenance during planned downtime.
• Maintenance Logs: Record battery changes in a logbook (Date, Axis, Voltage, Technician).

VIII. Common Pitfalls & Precautions

1. Pitfall: Replacing Battery Without Homing

• Consequence: The drive runs in relative mode, accumulating position errors.
• Fix: Always perform a homing sequence after battery replacement.

2. Pitfall: Using Non-Standard Batteries

• Consequence: AA/AAA batteries (1.5V) cannot power the encoder circuitry (requires 3.0V+).
• Fix: Strictly use CR2032 (3V) or the specific model recommended in the manual.

3. Pitfall: Ignoring the Bus Cable

• Consequence: Loose cables cause “ghost” battery alarms due to data corruption.
• Fix: Torque screws on connectors to 0.5 N·m and use thread locker if necessary.

4. Safety Precautions

• Electrical Shock: Always discharge the drive DC bus (wait 5 mins) before touching internal components.
• Data Loss: Some encoders lose parameters if power is removed too long. Replace batteries quickly (within 2 minutes) if the manual specifies “live replacement.”
• Professional Repair: Do not solder on encoder PCBs unless trained; ESD can destroy the chip.

IX. Conclusion

Alarm 27 in the ZSMC K-Series servo system is a critical indicator of battery voltage depletion leading to multi-turn position loss. While the fix often seems as simple as replacing a coin cell, the root causes range from environmental stress to hardware failures.

For engineers, mastering the voltage verification process, homing procedures, and environmental control is essential. As technology evolves, battery-less absolute encoders (using supercapacitors or energy harvesting) are emerging, promising to eliminate this issue entirely. However, until then, a proactive battery maintenance strategy is the most cost-effective way to ensure servo reliability.

Final Recommendation: Integrate battery checks into your daily “Gemba Walk” or start-up checklist. The cost of a CR2032 battery is negligible compared to the cost of a crashed machine or a day of lost production.

I. Introduction

In the field of industrial automation, the Zhengshun Servo ZS100 series is widely applied in core scenarios such as CNC machine tools, industrial robots, packaging machinery, and textile equipment due to its high precision, rapid response, and wide speed – regulation range. However, during long – term operation, the ERR45 fault (motor over – temperature) is one of the most common alarms in the ZS100 series. According to the fault statistics of a servo manufacturer in 2023, ERR45 accounts for 18% of all faults. If not handled promptly, it may lead to motor winding burnout, bearing seizure, and even equipment shutdown and production interruption, causing significant losses to enterprises.

Based on the technical documents of the ZS100 series, on – site maintenance experience, and fault cases, this article systematically analyzes the solution logic of the ERR45 fault from the perspectives of fault definition, detection principle, cause analysis, troubleshooting steps, and preventive measures, providing an actionable reference plan for engineering technicians.

II. Definition and Detection Principle of ERR45 Fault

1. Fault Definition

ERR45 is a protection alarm for abnormal motor temperature in the Zhengshun Servo ZS100 series drive. The trigger condition is that the motor temperature exceeds the threshold set by the drive (the default threshold is 130°C – 150°C, depending on the motor insulation class). When the temperature exceeds the threshold, the drive immediately cuts off the output, the panel displays “ERR45”, and locks the fault state (which can only be restarted after reset).

2. Temperature Detection Principle

The ZS100 series collects temperature signals through a built – in temperature sensor in the motor. There are two common types of sensors:

• PTC Thermistor (Positive Temperature Coefficient): At 25°C, its resistance is approximately 100Ω – 500Ω. As the temperature rises, the resistance increases sharply (the Curie point is about 120°C – 150°C). When it exceeds the Curie point, the resistance suddenly jumps to infinity, triggering protection.
• PT100 Platinum Resistor (Linear Characteristics): At 0°C, its resistance is 100Ω, with a temperature coefficient of about 0.00385Ω/Ω/°C and high precision (±0.1°C), suitable for high – precision temperature detection.

The temperature detection process of the drive is as follows:

• The sensor converts the temperature signal into a resistance value.
• The signal conditioning circuit (amplification and filtering) converts the resistance value into a voltage signal.
• The AD conversion chip (such as a 12 – bit AD) converts the voltage signal into a digital quantity.
• The internal algorithm of the drive converts the digital quantity into a temperature value (for example, the temperature calculation formula for PT100: T=R0​×αRt​−R0​​, where Rt​ is the current resistance, R0​ is the resistance at 0°C, and α is the temperature coefficient).
• The comparator compares the calculated temperature with the set threshold. If it exceeds the threshold, the ERR45 alarm is triggered.

III. In – Depth Cause Analysis of ERR45 Fault

The essence of ERR45 is that “the motor temperature exceeds the protection threshold”, but the reasons for the temperature rise need to be analyzed from six dimensions: the motor side, the fan side, the wiring side, the drive side, the load side, and the environmental side, as follows:

(I) Motor Side: Real Overheating or Sensor Fault

1. Real Overheating (Abnormal Motor Temperature)

• Overload Operation: When the load torque exceeds the rated torque of the motor (for example, the rated torque of the ZS100 – 22kW motor is 70N·m, and if the load reaches 80N·m, it is overloaded), the current increases (exceeding the rated current), and the winding heating increases.
• Long – term High – load Operation: The motor runs continuously for 24 hours, and the heat dissipation cannot keep up, causing the temperature to accumulate and exceed the threshold.
• Poor Heat Dissipation: Dust accumulation on the motor heat sink, coverage by debris (such as oil stains from cutting fluid splashing), or a high ambient temperature (workshop temperature > 40°C) reduce the heat dissipation efficiency.
• Motor Faults:
  • Winding Short – circuit: The insulation of the winding ages (the insulation life is halved for every 10°C increase in temperature), resulting in an inter – phase short – circuit, a sudden increase in current, and increased heating.
  • Bearing Damage: The bearing grease fails (carbonization due to high temperature) or the ball bearings wear, causing friction between the rotor and the stator and generating a large amount of heat.
  • Rotor Jamming: Foreign objects (such as iron filings) enter the motor, or the bearing seizes, preventing the rotor from rotating. The current increases sharply (up to 5 – 10 times the rated current), causing instant overheating.

2. Sensor Fault (False Temperature Alarm)

• Sensor Damage: The PTC thermistor breaks down (resistance is 0Ω), or the PT100 platinum resistor is open – circuit (resistance is infinite).
• Improper Sensor Installation: It is not tightly attached to the motor winding (for example, installed on the heat sink instead of near the winding), causing the detected temperature to be lower than the actual winding temperature.
• Sensor Type Mismatch: The drive parameters are set to “PT100”, but a PTC sensor is actually used, resulting in incorrect temperature calculation.

(II) Fan Side: Heat Dissipation Failure

The ZS100 series motor is usually equipped with a forced air – cooling fan (voltage AC220V, speed 1500rpm). Fan failure is a common cause of ERR45:

• Fan Does Not Rotate: The fan motor is damaged (winding burnout), or there is a power supply fault (loose wiring, fuse blowout).
• Insufficient Fan Speed: Dust accumulation on the fan blades (such as in a workshop with a lot of dust) or bearing wear (high rotational resistance) reduce the air volume (the normal air volume is about 0.5m³/min. If it drops to 0.2m³/min, heat dissipation fails).
• Incorrect Fan Direction: The fan rotates in reverse (such as due to incorrect wiring phase sequence), causing air to be blown out from the inside of the motor instead of being drawn in, completely losing the heat dissipation effect.

(III) Wiring Side: Signal Transmission Fault

Wiring problems of the temperature sensor can prevent the drive from correctly collecting the temperature signal:

• Broken Wire: The wire breaks due to long – term vibration (for example, the motor junction box is not fixed), or is squeezed by mechanical parts (such as the machine tool protective door clamping the wire).
• Poor Contact: The wiring terminals are oxidized (for example, copper terminals develop green rust), or the screws are loose, increasing the resistance (for example, the contact resistance increases from 0.1Ω to 10Ω), causing abnormal AD conversion values.
• Polarity Error: The PT100 sensor requires “three – wire” wiring (to compensate for wire resistance). If it is connected as “two – wire”, the detected temperature value will be higher (for example, the actual temperature is 100°C, but the detected temperature is 120°C).

(IV) Drive Side: Detection Circuit Fault

If the motor, fan, and wiring are all normal, a fault in the drive’s temperature detection circuit should be suspected:

• AD Conversion Chip Damage: For example, if the ADS1115 chip fails, the conversion of the resistance value to the temperature value is incorrect (for example, the actual temperature is 100°C, but it is displayed as 150°C).
• Comparator Fault: For example, if the LM393 comparator is damaged, the threshold judgment is incorrect (for example, the threshold is set to 140°C, but the comparator triggers the alarm at 120°C).
• Parameter Setting Errors:
  • The temperature threshold is set too low (for example, for an F – class insulation motor, the threshold is set to 120°C, while the actual allowable temperature is 155°C).
  • The sensor type is set incorrectly (for example, PTC is actually used, but the parameter is set to PT100).
  • The filtering time is set too short (for example, 10ms), causing temperature signal fluctuations and false alarms.

(V) Load Side: Mechanical Transmission Abnormalities

Mechanical load problems can indirectly cause motor overheating:

• Transmission Jamming: Poor lubrication of the lead screw (lack of oil) or bearing damage (ball bearing seizure) requires the motor to overcome greater resistance, increasing the current.
• Excessive Load: For example, the feeding mechanism of packaging machinery is jammed, causing the motor torque to exceed the rated value.
• Coupling Misalignment: The radial deviation between the motor shaft and the load shaft is > 0.05mm, and the axial deviation is > 0.03mm, causing the motor shaft to bear additional radial forces and increasing friction heating.

(VI) Environmental Side: Deterioration of Heat Dissipation Conditions

• High Workshop Temperature: In summer, if the workshop temperature exceeds 40°C, the motor’s heat dissipation capacity decreases (the heat dissipation efficiency is inversely proportional to the ambient temperature).
• Poor Ventilation: There are obstacles (such as shelves and equipment) around the motor, preventing the hot air from being discharged.
• Heat Source Interference: There are heaters, high – frequency welding machines, and other heat sources near the motor, increasing the ambient temperature.

IV. Systematic Troubleshooting Steps for ERR45 Fault

When troubleshooting ERR45, the principle of “from simple to complex and from external to internal” should be followed to avoid blind disassembly. The following is a standardized troubleshooting process:

Step 1: Reset the Fault and Confirm Whether It is a False Alarm

Operation: Press the “reset” key on the drive panel (or power off and restart). If the fault disappears, it may be due to occasional interference (such as power supply fluctuations or instantaneous abnormal sensor signals). If the fault recurs, further troubleshooting is required.

Step 2: Check the Temperature Sensor Wiring (Easiest to Check)

Tools: Multimeter (resistance range), screwdriver.
Operation:

• Turn off the drive power and wait for 5 minutes (for capacitor discharge).
• Remove the motor junction box and find the temperature sensor terminals (marked as “TH” or “TEMP”).
• For a PTC sensor (two wires): Measure the resistance between the two ends. At 25°C, it should be 100Ω – 500Ω (depending on the model). If the resistance is infinite (broken wire) or 0Ω (short – circuit), replace the wire or sensor.
• For a PT100 sensor (three wires): Measure the resistance between the “A – B” wires (about 100Ω at 25°C). The resistances between “A – C” and “B – C” wires should be equal (to compensate for wire resistance). If the resistances are abnormal, check the wiring or sensor.
• Check whether the terminals are oxidized or loose. Polish them with sandpaper or tighten them again.

Step 3: Check the Motor Fan (Key Heat – Dissipation Component)

Tools: Multimeter (voltage range), tachometer (or the “Tachometer” mobile app), compressed air.
Operation:

• Power on and start the motor (run at low speed), and observe whether the fan rotates.
• If the fan does not rotate: Measure the fan power supply voltage (should be AC220V). If there is no voltage, check the drive’s fan output terminals or wiring. If there is voltage, it means the fan motor is damaged and needs to be replaced.
• If the fan rotates: Use a tachometer to measure the speed (normal 1500rpm ± 10%). If the speed is insufficient, clean the blade dust with compressed air or lubricate the bearing (add a drop of engine oil).
• Check the fan direction: Feel the airflow with your hand. Air should be drawn in from the outside of the motor (blown from the heat sink to the inside of the motor). If it rotates in reverse, adjust the wiring phase sequence.

Step 4: Detect the Actual Motor Temperature (Determine Whether It is Overheated)

Tools: Infrared thermometer (such as FLUKE TiS75), megohmmeter (500V).
Operation:

• Run the motor until the fault is triggered (or simulate the load), and use an infrared thermometer to measure the motor housing (normal ≤ 80°C), heat sink (normal ≤ 100°C), and winding (measured through the junction box, normal ≤ 130°C, F – class insulation allows 155°C).
• If the temperature exceeds the threshold, it means the motor is really overheated, and the load or the motor itself needs to be checked.
• After shutdown, use a megohmmeter to measure the winding insulation resistance (between phases and to the ground). It should be > 10MΩ normally. If it is < 1MΩ, it means the winding is damp or the insulation is aged, and the motor needs to be dried or replaced.

Step 5: Troubleshoot the Load and Mechanical Transmission (Indirect Causes)

Tools: Torque sensor, dial indicator, lubricating grease.
Operation:

• Use a torque sensor to measure the load torque (for example, the rated torque of the ZS100 – 22kW motor is 70N·m. If it exceeds 80N·m, it is overloaded). Adjust the load (such as reducing the feeding amount or repairing the jammed lead screw).
• Use a dial indicator to measure the coupling alignment: the radial deviation should be ≤ 0.05mm, and the axial deviation should be ≤ 0.03mm. If it exceeds the standard, re – adjust the coupling.
• Check the lubrication of mechanical transmission components: whether the lead screw and bearings are short of oil. Add lubricating grease (such as lithium – based grease).
• Manually rotate the motor shaft (power off): if it is jammed, it means there is a problem with the bearing or rotor, and the motor needs to be disassembled for inspection.

Step 6: Check the Drive’s Temperature Detection Circuit (Last Step)

Tools: Oscilloscope, multimeter, replacement sensor.
Operation:

• If all the above steps are normal, disassemble the drive and find the temperature detection circuit (usually on the control board, marked as “TEMP IN”).
• Use an oscilloscope to measure the sensor signal waveform: the resistance change of the PTC sensor should be proportional to the temperature, and the voltage signal of the PT100 should change linearly.
• Replace the temperature sensor (use a new sensor of the same model). If the fault disappears, it means the original sensor is damaged.
• If the fault still exists, check the power supply voltage (should be 5V) and output signal of the AD conversion chip (such as ADS1115) for normality, or replace the control board.

Step 7: Improve the Environment and Heat Dissipation (Prevent Recurrence)

Tools: Thermometer, ventilation equipment, compressed air.
Operation:

• Measure the workshop temperature. If it is > 40°C, install an air conditioner or industrial fan (aimed at the motor heat sink).
• Clean the debris around the motor (such as cutting fluid buckets and tools) to ensure a clear heat dissipation channel.
• Apply thermal conductive silicone grease (such as Shin – Etsu 7921) on the motor heat sink to improve heat dissipation efficiency.
• For motors that run under long – term high – load conditions, add an external heat sink (such as an air – cooled heat sink).

V. Analysis of Typical Cases

Case 1: False Alarm Due to Wiring Breakage

Fault Phenomenon: A ZS100 – 15kW servo motor on a CNC lathe suddenly reported ERR45 during operation and could not be started after reset.
Troubleshooting Process:

• Check the temperature sensor wiring and find that one wire of the PTC sensor is broken at the junction box (due to long – term vibration, the wire – terminal welding joint is detached).
• Re – weld the wire and perform insulation treatment (wrap it with heat – shrinkable tubing).
• Power on for testing, and the fault disappears. The motor returns to normal.
  Cause: The wire breakage interrupts the sensor signal, and the drive misjudges it as “infinite temperature”, triggering ERR45.
  Lesson: The motor junction box should be firmly fixed to prevent wire breakage due to vibration.

Case 2: Overheating Due to Fan Dust Accumulation

Fault Phenomenon: A ZS100 – 7.5kW servo motor on a packaging machine frequently reported ERR45 (1 – 2 times a day). It could continue to run after reset, but the frequency gradually increased.
Troubleshooting Process:

• Check the fan and find that the blades are covered with dust (the workshop is a flour mill with a lot of dust), and the speed is only 800rpm (normal 1500rpm).
• Clean the fan blades with compressed air and add lubricating grease to the bearing.
• Run for 24 hours, and the fault does not recur.
  Cause: Dust accumulation on the fan reduces the speed and heat dissipation capacity, causing the motor temperature to gradually rise to the threshold.
  Lesson: In dusty environments, the fan should be cleaned regularly, preferably once a month.

Case 3: Real Overheating Due to Load Overload

Fault Phenomenon: A ZS100 – 22kW joint motor on an industrial robot reported ERR45. The infrared thermometer showed that the motor temperature reached 160°C (exceeding the 155°C allowed for F – class insulation).
Troubleshooting Process:

• Check the load and find that the lubrication of the robot’s lead screw is poor, causing the torque to increase from 70N·m to 90N·m (overload).
• Disassemble the lead screw, clean the old lubricating grease, and add new lithium – based grease.
• Adjust the load (reduce the grasping weight of the robot arm). After operation, the torque returns to 70N·m, and the temperature drops to 110°C.
  Cause: Load overload increases the motor current (from 46.5A to 55A), increasing the winding heating and exceeding the temperature threshold.
  Lesson: The load torque should be monitored regularly to avoid long – term overload operation.

VI. Preventive Measures for ERR45 Fault

1. Regular Maintenance Plan (Key)

2. Parameter Setting Optimization

• Temperature Threshold: Set it according to the motor insulation class (set it to 140°C for F – class and 160°C for H – class) to avoid false alarms due to a too – low threshold or loss of protection due to a too – high threshold.
• Sensor Type: Ensure that the drive parameters are consistent with the actual sensor (set PTC as “PTC” and PT100 as “PT100”).
• Filtering Time: Set it to 100ms – 500ms (avoid false alarms due to signal fluctuations), but not too long (such as > 1s, which will delay protection).

3. Environmental Improvement

• Control the workshop temperature within 25°C – 35°C (install an air conditioner or industrial fan).
• Prohibit stacking debris within 1 meter around the motor to ensure a clear heat dissipation channel.
• For high – temperature environments (such as foundry workshops), add a water – cooled heat sink to the motor (instead of air – cooling).

4. Load Monitoring

• Install a torque sensor or current sensor to monitor the motor load in real – time (alarm when the torque exceeds 110% of the rated value).
• Set overload protection (set the “overload current threshold” in the drive parameters, such as 120% of the rated current. When it is exceeded, cut off the output).
• Avoid frequent start – stop (for example, starting more than 5 times per minute will cause heat accumulation in the motor).

VII. Conclusion

The ERR45 fault is a “temperature protection signal” for the ZS100 series servo system, and its core logic is that “the motor temperature exceeds the safety threshold”. When troubleshooting, start with simple components such as wiring and fans, and gradually delve into the motor, load, and drive. Use tools (multimeter, infrared thermometer, oscilloscope) to quickly locate the fault point.

The key to preventing ERR45 is regular maintenance (cleaning the fan and checking the wiring), optimizing parameters (correctly setting the temperature threshold), improving the environment (controlling the workshop temperature), and monitoring the load (avoiding overload). Engineering technicians should master the detection principle and troubleshooting process of the fault to solve problems in a timely manner and ensure the stable operation of the equipment.

For ZS100 series users, it is recommended to establish a fault record (record the fault time, phenomenon, troubleshooting process, and solution), and take preventive measures in advance (such as cleaning the fan before summer) through data statistical analysis (such as the high – incidence season and equipment of ERR45).

Introduction

In the field of industrial automation, servo drives serve as the core hub between hydraulic systems and motor control. Their stability directly determines the production efficiency of equipment such as machine tools, injection molding machines, and packaging machinery. As a mainstream product in the domestic low-to-mid-end market, the Zhensun Servo ZS100 series is widely used in various hydraulic drive scenarios due to its high cost-performance ratio. However, ERR46 (Hydraulic Pressure Sensor Fault) is one of the most frequently reported issues by users. This fault causes the servo system to shut down immediately, potentially interrupting production processes or, in severe cases, damaging hydraulic components (e.g., pumps, valves).

This article combines Zhensun Servo technical documentation, on-site maintenance cases, and sensor principles to provide a comprehensive breakdown of the ERR46 fault from four dimensions: fault mechanism, cause investigation, resolution steps, and preventive measures, offering maintenance personnel an actionable troubleshooting guide.

1. The Underlying Logic of ERR46: The “Perception-Feedback” Mechanism of the Hydraulic Pressure Sensor

To resolve ERR46, one must first understand the role of the hydraulic pressure sensor and the drive’s fault-triggering logic.

1.1 Core Function of the Hydraulic Pressure Sensor

The hydraulic pressure sensor acts as the “nerve ending” of the hydraulic system. Essentially, it is a pressure-to-electrical signal converter. The ZS100 series typically employs piezoresistive sensors (low cost, high reliability). The working principle is as follows: when hydraulic oil pressure acts on the sensor’s sensitive diaphragm, the diaphragm deforms, causing a change in the resistance of the internal piezoresistive elements. This change is converted into a 0-10V DC analog signal (or 4-20mA for some models) via a Wheatstone bridge and fed back to the servo drive.

The drive adjusts the motor speed based on this signal to ensure the hydraulic system pressure remains stable within the set range (e.g., 10-15MPa for machine tool clamping mechanisms, 0.5-1MPa for lubrication systems). For example:

• When clamping cylinder pressure is insufficient, the drive increases motor speed to boost the pump’s output pressure.
• When the pressure reaches the set value, the drive reduces speed to maintain constant pressure.

1.2 Trigger Conditions for ERR46

The ZS100 series drive collects sensor signals through analog input channels (e.g., parameter L0.11). Internal signal detection circuits monitor the following metrics in real-time:

• Range: Whether the sensor signal exceeds the drive’s set threshold (e.g., if 0-10V corresponds to 0-10MPa, a signal exceeding 10V triggers an over-range alarm).
• Signal Stability: Whether signal fluctuation exceeds 0.5V within 1 second (e.g., signal jitter caused by vibration).
• Signal Continuity: Whether “signal loss” occurs (e.g., wiring disconnection resulting in a sustained 0V signal for over 1 second).
• Parameter Matching: Whether the sensor’s zero point (voltage at no pressure) and full scale (voltage at max pressure) match the drive parameters.

If any of these metrics are abnormal, the drive triggers an ERR46 fault and cuts off motor output to prevent the hydraulic system from running out of control and damaging equipment.

2. Common Causes and Troubleshooting Process for ERR46

Based on field maintenance data, the top three causes of ERR46 are: loose wiring (45%), sensor damage (30%), and parameter errors (20%). The remaining 5% are attributed to internal drive circuit faults (e.g., damage to the analog input module). Below is the standardized troubleshooting process:

2.1 Step 1: Safety First (Mandatory!)

Servo drives contain high-voltage capacitors (which may retain over 300V even after power-off). Before operation:

1. Disconnect the drive’s main power supply (AC380V).
2. Wait for 5 minutes to allow the capacitors to discharge.
3. Use a multimeter to measure the voltage at the drive terminals (e.g., L1, L2, L3) to confirm they are de-energized before proceeding.

2.2 Step 2: Check Sensor Wiring (Most Common Cause)

Wiring issues are the “number one killer” of ERR46 faults, especially in high-vibration environments (e.g., machine tools) where terminal looseness and cable damage are common.

Troubleshooting Steps:

1. Locate Terminals: Open the drive panel and find the hydraulic pressure sensor terminals (usually marked “PRESSURE SENSOR” or “OIL PRESSURE,” corresponding to terminals like X3-1 (+24V), X3-2 (Signal Output), X3-3 (0V/GND)).
2. Check for Looseness: Gently shake the terminals with a screwdriver. If poor contact between the terminal and wire core is found (e.g., exposed core), re-crimp or replace the terminal.
3. Check Cable Integrity: Inspect the sensor cable for crushing, breaking, or fraying (especially near bends close to the sensor or drive). Use a multimeter continuity setting to test the cable (signal wire resistance should be <0.5Ω).
4. Check Shielding: The sensor cable must be shielded, with the shield grounded at a single point (drive side) to avoid electromagnetic interference (e.g., crossing motor cables and sensor cables causes signal fluctuation).

Case Study: A CNC lathe user reported an ERR46 fault. Inspection revealed that the signal wire terminal (X3-2) was loose due to vibration, causing poor contact between the core wire and terminal. After tightening the terminal and wiping the oxidation layer with alcohol, the fault was resolved.

2.3 Step 3: Test Sensor Output Signal (Core Cause)

If wiring is normal, verify if the sensor can perceive pressure correctly. The standard output for ZS100 series sensors is: 0MPa = 0V, Full Scale (e.g., 10MPa) = 10V, with a linear relationship between output and pressure.

Troubleshooting Steps:

1. Power the Sensor: The sensor requires an external 24V DC power supply (if not provided by the drive, supply separately; note polarity: Red to +24V, Black to 0V).
2. Apply Pressure: Use a manual pump or the equipment’s hydraulic system to apply pressure to the sensor (gradually increasing from 0MPa to full scale).
3. Measure Output: Use a multimeter DC voltage setting to measure the signal terminal (X3-2) and observe voltage changes:
   • Normal: Voltage increases by 1V for every 1MPa increase in pressure (e.g., 10MPa corresponds to 10V).
   • Abnormal 1: Voltage remains 0V → Sensor power not connected or internal short circuit.
   • Abnormal 2: Voltage remains 10V → Sensor range setting error or internal open circuit.
   • Abnormal 3: High voltage fluctuation (e.g., >0.5V within 1s) → Aging of sensitive elements or interference.
   • Abnormal 4: Non-linear voltage (e.g., pressure increases but voltage stays flat) → Damaged piezoresistive chip.

Case Study: An injection molding machine triggered ERR46. Testing revealed the sensor output remained at 0V even when pressure was applied (it should be 0V at no pressure but increase under load). Replacing the piezoresistive sensor (0-10V, 0-10MPa) resolved the fault.

2.4 Step 4: Check Drive Parameters (Often Overlooked)

Parameter errors can cause the drive to misjudge a normal sensor signal. Key parameters related to the hydraulic pressure sensor in the ZS100 series are:

Troubleshooting Steps:

1. Enter Parameter Mode: Press the “Programming” key on the panel and enter the password (default “1234”).
2. Check L0.11: Confirm the correct analog channel is selected (e.g., “1” for X3 terminal).
3. Check L0.12: Confirm the range matches the sensor (e.g., “10.0” for a 0-10MPa sensor).
4. Check L0.13/L0.14: Confirm zero (0.0V) and full scale (10.0V) are at defaults (if modified, restore them).
5. Restore Factory Settings: If parameters are chaotic, set L9.00 (Factory Reset) to “1” and restart the drive to restore defaults.

Case Study: A packaging machine operator accidentally changed L0.12 from “10.0” to “5.0”. The drive interpreted the full-scale pressure as 5MPa. When actual pressure reached 6MPa (outputting 6V), the drive judged it as “over-range” and triggered ERR46. Restoring L0.12 to “10.0” fixed the issue.

2.5 Step 5: Factory Reset and Self-Learning (Ultimate Solution)

If the above checks fail, the issue may be sensor characteristic changes (e.g., zero drift due to aging) or corrupted drive parameters. Re-calibration via self-learning is required.

Operation Steps:

1. Restore Factory Settings: Set L9.00 to “1” and restart the drive (parameters return to default).
2. Enable Self-Learning: Set L0.15 to “1”.
3. Collect Zero Signal: Open the hydraulic system relief valve to ensure 0MPa pressure. The drive automatically collects the zero-point voltage (e.g., 0V) and saves it to L0.13.
4. Collect Full Scale Signal: Close the relief valve and apply full-scale pressure (e.g., 10MPa) to the system. The drive collects the full-scale voltage (e.g., 10V) and saves it to L0.14.
5. Exit Self-Learning: Set L0.15 to “0” and save parameters (press “Confirm”).

Note: Ensure correct wiring and stable power before self-learning. Inaccurate results will occur if pressure exists during zero collection (causing subsequent signal offsets).

3. Preventive Measures for ERR46: From “Passive Repair” to “Active Prevention”

The root cause of ERR46 is often poor daily maintenance. The following measures can reduce the failure rate by 80%:

3.1 Daily Maintenance: Regular Inspections

• Weekly: Check if sensor terminals are loose and if cables are damaged.
• Monthly: Wipe the sensor surface with alcohol to remove oil and dust, preventing contamination of sensitive elements.
• Quarterly: Calibrate the sensor using a standard pressure source (e.g., piston manometer) to ensure output accuracy (error ≤ ±1%).
• Semi-Annually: Check the stability of the sensor power supply (24V DC); voltage fluctuation should not exceed ±5%.

3.2 Operational Standards: Avoid Misoperation

• Prohibit Arbitrary Parameter Changes: Only trained personnel should modify parameters. Only process-related parameters (e.g., pressure setpoints) should be adjusted; core parameters like sensor range (L0.12) and zero offset (L0.13) must not be altered.
• Pressure Release After Shutdown: Always open the hydraulic relief valve after stopping the equipment to release pressure (prevents long-term high-pressure damage to the sensor).
• Pre-Start Check: Verify sensor wiring and power are normal before startup; ensure no fault codes are present.

3.3 Environmental Control: Reduce Interference

• Vibration Damping: Add rubber damping pads at the sensor installation site to prevent vibration from loosening wiring or damaging the sensor.
• Cabling: Route sensor cables separately from motor cables and power lines (spacing ≥10cm) to avoid electromagnetic interference.
• Temperature: Keep the sensor operating temperature between -20°C and 85°C (install cooling fans for high-temp environments or insulation for low-temp environments).

4. Extended Analysis: Correlation with Other Faults

ERR46 rarely occurs in isolation and may happen simultaneously with the following faults, requiring comprehensive investigation:

• ERR45 (Overvoltage Fault): If hydraulic pressure exceeds the sensor range, it may trigger both ERR46 (sensor over-range) and ERR45 (DC bus overvoltage).
• ERR12 (Undervoltage Fault): Undervoltage in the sensor power supply (24V DC) causes abnormal output signals, triggering ERR46.
• ERR03 (Overcurrent Fault): If a sensor signal error causes the drive to misjudge low pressure, the motor may run at high speed continuously, leading to overcurrent.

5. Conclusion

ERR46 is a “high-frequency fault” in the Zhensun Servo ZS100 series, but it is not a “difficult disease.” Its core logic is “abnormal sensor signal.” Troubleshooting should follow the sequence of Wiring → Sensor → Parameters to narrow down the fault range step-by-step.

For maintenance personnel, mastering the ERR46 troubleshooting method not only resolves downtime quickly but also reduces recurrence through daily maintenance and operational standards, saving significant repair costs and downtime for enterprises.