Inovance MD300/MD300N Series Inverter User Guide: Operation Panel, Terminal Control and Fault Troubleshooting

The Inovance MD300/MD300N series is a modular, high-performance general-purpose inverter designed for a wide range of industrial motor control applications. This guide provides a comprehensive overview of the MD300/MD300N operation panel, terminal wiring configuration, parameter settings, communication interfaces, and fault code diagnostics to help users install, configure, and maintain their inverters effectively.

1. Introduction

The MD300 series represents Inovance’s next-generation modular inverter platform. Unlike traditional inverters that require multiple product lines to cover different performance tiers, the MD300 uses a flexible modular architecture that allows customers to customize functionality through a single platform. The MD300N is the upgraded version featuring improved exterior design and structural enhancements while maintaining full functional compatibility with the MD300.

The inverter series supports two primary control modes:

• Sensorless Vector Control (SVC): Open-loop vector control suitable for high-performance applications requiring precise speed and torque control, such as machine tools, centrifuges, and wire drawing machines.
• V/F Control: Voltage-to-frequency control ideal for general-purpose applications where high precision is not critical, such as fans, pumps, and multi-motor drives.

Key technical specifications include a maximum output frequency of 300 Hz, carrier frequency adjustable from 0.5 kHz to 16 kHz, and start torque of 150% at 0.5 Hz. The speed regulation range reaches 1:100 under SVC mode with steady-speed accuracy of ±0.5%. Overload capacity is rated at 150% of rated current for 60 seconds and 180% for 1 second, providing robust protection during demanding start-up and braking operations.

The product line covers a wide power spectrum: single-phase 220V models from 0.4 kW to 2.2 kW (designated MD300S/MD300NS), and three-phase 380V models from 0.75 kW to 90 kW (designated MD300T/MD300NT). All models operate with an input voltage tolerance of -15% to +20%.

The MD300 series features independent air duct design with optional heatsink installation inside or outside the cabinet, achieving near-IP54 protection. It supports common DC bus operation through direct DC bus terminals and fan DC power supply compatibility. A user password protection system, quick-menu design, and standard RJ45 interface for both the external keypad and communication port further enhance usability while reducing application costs.

2. LED Operation Panel

The MD300/MD300N features a 5-digit LED operation panel that enables parameter modification, operating status monitoring, and run/stop control. The panel can be mounted directly on the inverter or remotely connected via a standard RJ45 cable (up to 3 meters standard, extendable), allowing flexible installation in control cabinets or on external door panels.

2.1 Panel Layout and Indicators

The LED panel includes multiple status indicators grouped into function lights and unit lights:

Function Indicators:

• RUN: Off when the inverter is stopped; illuminated when running.
• LOCAL/REMOT: Off indicates keypad control mode; on indicates terminal control mode. Also reflects remote communication control status.
• FWD/REV: Off indicates forward rotation; on indicates reverse rotation.
• TUNE/TC: Blinks during motor parameter auto-tuning; on indicates torque control mode; off indicates speed control mode.

Unit Indicators:

• Hz – Frequency unit
• A – Current unit
• V – Voltage unit
• RPM – Speed unit
• % – Percentage unit

The 5-digit LED display shows the set frequency, output frequency, various monitoring data, and alarm/fault codes. The panel displays different parameters depending on whether the inverter is in stop mode or run mode.

2.2 Keypad Buttons

2.3 Menu Navigation

The MD300 uses a three-level menu structure for parameter access:

1. First Level (Parameter Group): Function parameter groups such as F0 (Basic), F1 (Motor), F2 (Vector/VF Control), F3 (Terminal I/O), F4 (Start/Stop), F5 (Fault/Protection), F6 (Auxiliary), FF (Manufacturer), and FP (User Password).
2. Second Level (Function Code): Individual parameters within each group, e.g., F0-00 (Control Mode).
3. Third Level (Setting Value): The actual value assigned to the parameter.

When at the third level, pressing ENTER saves the parameter and advances to the next function code, while pressing PRG returns to the second level without saving. Parameters that cannot be modified will not show a blinking digit when entered.

2.4 Status Display

In stop mode, pressing the shift key cycles through five parameters: set frequency, DC bus voltage, DI input status, AI1 voltage, and AI2 voltage. In run mode, seven parameters are available: running frequency, DC bus voltage, output voltage, output current, DI input status, AI1 voltage, and AI2 voltage.

The terminal status display uses a decimal value where each bit represents a terminal state: BIT0 for DI1, BIT1 for DI2, BIT2 for DI3, BIT3 for DI4, BIT6 for RELAY output, and BIT7 for DO output. When a bit equals 1, the corresponding terminal is active.

2.5 Password Protection

Parameter security is managed through function code FP-00. Setting a non-zero value activates password protection. Once enabled, attempting to enter the programming menu displays “—–” and requires the correct password. To disable protection, enter the correct password and set FP-00 to 0.

3. Terminal Control and Wiring

The MD300/MD300N provides comprehensive terminal options for both main circuit power connections and control signal interfaces. Proper wiring is essential for safe and reliable operation.

3.1 Main Circuit Terminals

Single-Phase Models (220V):

Three-Phase Models (380V):

3.2 Control Circuit Terminals

Power Supply Terminals:

• +10V - GND: Provides +10V power supply (max 10mA), typically for external potentiometer.
• +24V - COM: Provides +24V power supply (max 200mA) for digital I/O and external sensors.

Analog Input Terminals:

• AI1 - GND: 0V to 10V voltage input, input impedance 100kΩ.
• AI2 - GND: Selectable 0V to 10V or 4mA to 20mA via J3 jumper. Input impedance: 100kΩ (voltage mode) or 500Ω (current mode).

Digital Input Terminals:

• DI1: Digital input 1 (default: Forward Run FWD)
• DI2: Digital input 2 (default: Forward Jog FJOG)
• DI3: Digital input 3 (default: Multi-speed 1)
• DI4: High-speed pulse input (default: Multi-speed 2), max 50kHz

Output Terminals:

• AO - GND: Analog output, selectable voltage or current via J4 jumper. Configurable to output running frequency, set frequency, output current, pulse input, AI1, or AI2.
• DO - COM: Digital (open-collector) output, 0V to 24V, 0mA to 50mA.
• T/A - T/B: Relay normally closed contact
• T/A - T/C: Relay normally open contact (AC250V/3A/COSφ=0.4 or DC30V/1A)

3.3 Control Mode Wiring

The MD300 supports two terminal control modes configured via F3-00:

Two-Wire Mode (Default): FWD and REV terminal commands directly control motor direction. The inverter runs when a direction terminal is active and stops when released (or via separate stop command depending on configuration).

Three-Wire Mode: Uses a separate enable terminal (DIn, configured as function 3) plus FWD and REV terminals. The enable terminal must remain closed for operation; direction is controlled by momentary pulses on FWD or REV. To stop, the enable terminal must be opened.

3.4 Wiring Best Practices

• Use shielded cables for analog signal wiring and keep cable length under 20 meters.
• Install filter capacitors or ferrite rings at the analog signal source side if severe interference is present.
• Use reliable contact-type switches for digital inputs; avoid open-collector outputs unless properly isolated.
• When driving relays with DO output, install suppression diodes across the relay coil to prevent 24V power supply damage.
• Separate power wiring from control signal wiring; do not bundle them together.

4. Parameter Settings

The MD300 organizes parameters into functional groups. Understanding these groups is essential for proper configuration.

4.1 F0 Group — Basic Parameters

This group contains the most fundamental inverter settings:

• F0-00 Control Mode: Select SVC (0) for high-performance vector control or V/F (2) for general-purpose control. SVC requires motor parameter auto-tuning.
• F0-01 Command Source: Choose keypad control (0, LOCAL/REMOT LED off) or terminal control (1, LED on).
• F0-02 Main Frequency Source: Options include digital setting (non-volatile or volatile), pulse input (DI4), AI1, AI2, or multi-speed.
• F0-04 Digital Preset Frequency: Initial frequency value when digital setting is selected.
• F0-05 / F0-06 Acceleration / Deceleration Time: Range 0.0s to 3000.0s, defining the time from 0Hz to maximum frequency and vice versa.
• F0-07 V/F Curve: Select linear V/F (0) for constant torque loads or squared V/F (2) for fan/pump loads.
• F0-08 V/F Torque Boost: Set 0.0 for automatic boost, or manually adjust 0.1% to 30.0%. Avoid exceeding 8% to prevent overheating.
• F0-09 to F0-12 DI Terminal Function Selection: Assign functions such as forward/reverse run, jog, multi-speed, external fault, reset, and UP/DOWN to DI1-DI4.
• F0-13 DO Output Selection: Configure digital output for run status, fault, or frequency arrival.
• F0-14 AO Output Selection: Configure analog output source.
• F0-15 / F0-16 Start / Stop Mode: Choose direct start or speed tracking restart; select deceleration stop or free stop.

4.2 F1 Group — Motor Parameters

Accurate motor parameter entry is critical, especially for vector control:

• F1-00 Motor Type: Standard asynchronous, variable-frequency asynchronous, or permanent magnet synchronous (reserved).
• F1-01 to F1-05: Rated power, rated voltage, rated current, rated frequency, and rated speed — enter exactly as shown on the motor nameplate.
• F1-06 to F1-10: Stator resistance, rotor resistance, leakage inductance, mutual inductance, and no-load current. These are automatically updated after auto-tuning.
• F1-11 Tuning Selection: Set to 1 for static tuning (motor connected to load) or 2 for complete tuning (motor must be disconnected from load, running unloaded).

4.3 F2 Group — Vector and V/F Control Parameters

Vector Control Parameters (F0-00 = 0):

• F2-00 / F2-01: Speed loop proportional gain and integral time below switch frequency 1 (F2-02, default 5Hz).
• F2-03 / F2-04: Speed loop proportional gain and integral time above switch frequency 2 (F2-05, default 10Hz).
• F2-06: Slip compensation coefficient — increase if speed drops under heavy load.
• F2-07: Speed loop filter time / V/F AVR selection.
• F2-08: Torque upper limit (5.0% to 200.0%, default 150%).

V/F Control Parameters (F0-00 = 2):

• F2-09: Slip compensation coefficient for V/F mode.
• F2-10: Oscillation suppression gain — start at 0 and increase only if motor oscillation occurs.

4.4 F3 Group — Terminal I/O Parameters

This group configures terminal behavior:

• F3-00: Terminal control mode — two-wire (0) or three-wire (1).
• F3-01: UP/DOWN rate when using terminal frequency adjustment.
• F3-02 to F3-09: AI curve definition points — configure minimum, middle, and maximum input voltages and their corresponding percentage outputs.
• F3-10: Maximum pulse input frequency (0.00 to 50.00 kHz).
• F3-11: Input filter time.
• F3-12 / F3-13: AO zero offset and gain for analog output calibration.

4.5 F5 Group — Protection Parameters

• F5-00 / F5-01: Motor overload protection enable and coefficient.
• F5-02 / F5-03: Overvoltage stall gain and point (120% to 150%).
• F5-04 / F5-05: Overcurrent stall gain and point (100% to 200%).
• F5-06 / F5-07: Fault auto-reset count (0 to 3) and interval time.
• F5-08: Input phase loss protection (available on 18.5kW and above).
• F5-09: Load drop protection — when enabled, output frequency drops to 2Hz if no load is detected.

4.6 F6 Group — Auxiliary Functions

• F6-00: Maximum output frequency (50.00 to 300.00 Hz).
• F6-01 / F6-02: Upper and lower frequency limits.
• F6-03: Carrier frequency (0.5 to 16.0 kHz) — lower for reduced interference, higher for reduced motor noise.
• F6-04 to F6-06: Jog frequency, acceleration time, and deceleration time.
• F6-07: Reverse control enable/disable.
• F6-11: MF.K key function assignment.
• F6-14 to F6-17: Multi-speed 0 through 3 frequency settings.

5. Communication Configuration

The MD300/MD300N integrates communication capability through a standard RJ45 interface. The default factory protocol is MODBUS, making it straightforward to connect to PLCs, HMIs, and SCADA systems.

Key communication features include:

• Standard Interface: Both the operation panel extension port and the communication port use standard RJ45 connectors, ensuring reliability and reducing cabling costs.
• MODBUS RTU: The default出厂 protocol supports standard MODBUS RTU communication for reading and writing parameters, controlling run/stop, and monitoring status.
• Expansion Cards: Optional communication expansion cards are available to support PROFIBUS, DeviceNet, and CANopen fieldbus protocols.
• Command Channels: The inverter can receive run commands and frequency references through the communication interface when configured appropriately.

The LOCAL/REMOT LED indicator on the panel reflects the active command source. When communication control is active, the system operates in remote mode. Users can switch between local (keypad) and remote (communication/terminal) control through parameter configuration or the MF.K key if programmed for channel switching.

For reliable communication:

• Use shielded twisted-pair cables for RS-485 wiring.
• Install termination resistors at both ends of the bus.
• Keep communication cables separate from power cables to avoid electromagnetic interference.
• Ensure proper grounding of all devices on the network.

6. Fault Codes and Troubleshooting

The MD300/MD300N provides 20 protective functions. When a fault occurs, the inverter stops output, the fault relay activates, and the fault code displays on the LED panel. Below is a comprehensive reference for fault diagnosis.

6.1 Fault Code Reference Table

6.2 Common Fault Handling Procedures

No Display After Power-On:

1. Verify input power matches the inverter rated voltage using a multimeter.
2. Check the three-phase rectifier bridge; if damaged, contact service.

Input Circuit Breaker Trips After Power-On:

1. Inspect input power for ground faults or short circuits.
2. Test the rectifier bridge for breakdown; replace if necessary.

Motor Does Not Rotate After Inverter Starts:

1. Check for balanced three-phase output voltage at U, V, W. If present, inspect motor wiring and mechanical load.
2. If output is unbalanced, the drive board or output module may be damaged — contact service.
3. If no output voltage is present, the drive board or output module may be faulty.

Circuit Breaker Trips During Operation:

1. Check for short circuits between output phases or to ground.
2. If the inverter and motor are far apart, install an output AC reactor.

6.3 Preventive Maintenance

Regular maintenance extends inverter life and prevents unexpected failures:

• Daily: Check for abnormal motor noise or vibration; verify cooling fan operation; ensure no overheating.
• Periodic: Clean dust from the inverter surface and heatsink; inspect and tighten terminal screws; check for corrosion or arc marks on terminals; perform insulation tests on the main circuit.
• Component Replacement: Cooling fans typically last 2 to 3 years; electrolytic capacitors last 4 to 5 years. Monitor for abnormal noise, vibration, or leakage as indicators for replacement.

If a stored inverter is not used for more than two years, energize it for at least 5 hours using a voltage regulator to slowly raise voltage to rated value, preventing electrolytic capacitor degradation.