MITSUBISHI ELECTRIC FR-A500 frequency converter

MITSUBISHI ELECTRIC FR-A500 Inverter Complete Application Guide

Product positioning and technical overview

The Mitsubishi FR-A500 series transistor frequency converter is a variable voltage/frequency (VVVF) drive device designed for three-phase induction motors, widely used in the field of industrial automation. This series covers a power range of 0.4kW to 55kW and is divided into 200V class (FR-A520) and 400V class (FR-A540), supporting constant torque and variable torque load characteristics. FR-A500 adopts advanced PWM control technology, integrating V/F control, advanced magnetic flux vector control, and rich I/O interfaces, which can meet complex application needs from simple fans and pumps to high-precision positioning, lifting machinery, and more.

Compared with the previous generation product, FR-A500 has strengthened its automatic adjustment functions, such as offline/online self-tuning, intelligent mode selection, PID control, brake sequence control, and multiple fieldbus and communication interfaces (RS-485, Profibus DP, DeviceNet, CC Link, etc.), making it highly compatible and scalable in modern factory automation systems. This guide will systematically explain the installation specifications, electrical connections, operation panel usage, core parameter settings, fault diagnosis, and daily maintenance points of the frequency converter based on the official user manual.

Safety and Installation Standards

2.1 Safety level and precautions

Before using FR-A500, it is necessary to read and understand the safety instructions in the manual. The internal capacitor of the frequency converter will still maintain a dangerous voltage (up to 760VDC) after power failure, so it is necessary to wait for the POWER indicator light to turn off after 10 minutes of power failure, and use a multimeter to confirm that the voltage between the P-N terminals of the main circuit is below 30VDC before maintenance or wiring changes can be made.

Main safety warning:

It is strictly prohibited to install power factor compensation capacitors or surge suppressors on the output side (U, V, W) of the frequency converter, otherwise it may damage the frequency converter or capacitors.

The grounding of the frequency converter must be independent and meet the national electrical specifications (NEC 250 or IEC 536 Class I), and the size of the grounding wire must be at least equal to the recommended value corresponding to the motor capacity.

When selecting the "retry function" or "instantaneous stop and restart", the frequency converter will automatically restart after an alarm, and safety protection isolation must be set up, and an accompanying warning label must be affixed.

Vertical lifting applications must use mechanical brakes and cooperate with brake sequence functions to prevent gravity from falling.

2.2 Installation environment and mechanical dimensions

FR-A500 adopts an IP20 enclosed structure (standard), with an optional IP40 fully enclosed structure accessory (FR-A5CV). The installation conditions must meet:

Environmental temperature: constant torque load -10 ℃ to+50 ℃; Variable torque load -10 ℃ to+40 ℃.

Relative humidity: below 90% RH (no condensation).

Altitude: rated operation at ≤ 1000m; For every 500m increase between 1000-2500m, the rating will decrease by 3%.

Vibration: ≤ 5.9m/s ² (compliant with JIS C 0040).

Installation direction: Vertical installation, with sufficient heat dissipation space reserved in front, back, left, and right (100mm above, 120mm below, and 50mm above left and right).

The external dimensions of the frequency converter vary according to the power range, ranging from compact models (0.4kW) with a width of 110mm and a height of 260mm to high-power models (55kW) with a width of 480mm and a height of 700mm. DIN rail installation is suitable for models of 22kW and below.

Detailed explanation of electrical wiring

3.1 Main circuit wiring

The main circuit terminals include:

R. S, T: Three phase AC power input (200V or 400V level). For single-phase power supplies, only the R and S terminals can be connected.

U. V, W: Output of frequency converter, connected to three-phase induction motor. The phase sequence affects the direction of motor rotation, and when given a positive direction (STF signal), the motor rotates counterclockwise (as viewed from the load side).

P/+, P1: DC reactor (FR-BEL) connection. When leaving the factory, there is a short connector between P-P1, which must be removed when using a DC reactor.

P/+, PR: Built in braking resistor connection (limited to models 7.5kW and below). When higher braking capacity is required, the short-circuit between PR-PX can be removed, an external high inertia braking resistor (FR-ABR) can be connected, and Pr.30=1 and Pr.70=10% can be set.

P/+, N/-: Used when connected to an external braking unit (FR-BU), high power factor rectifier (FR-HC), or power regeneration common converter (FR-CV). Connecting to the opposite polarity will damage the frequency converter.

R1, S1: Control circuit independent power input terminal. When the main circuit is powered off and still needs to maintain alarm output, remove the short circuiting wires of R-R1 and S-S1, and provide power of the same voltage level from the primary side of MC.

Wiring selection (75 ℃ copper cable):

0.4K~2.2K: 1.5mm ² cable, 4mm crimping terminal, tightening torque of 1.5 N · m.

5.5K~7.5K：3.5~5.5mm²， Tightening torque of 2.5 N · m.

High power range (above 30K): 60-150mm ², tightening torque 8-24 N · m.

Important precautions:

The power cord must be connected to R, S, T, and it is strictly prohibited to connect it to U, V, W, otherwise the frequency converter will be immediately damaged.

The total wiring length on the output side should not exceed 500m. If it is too long, it will generate excessive charging current, which may trigger overcurrent protection by mistake. Suggestion: Non low noise mode 300m (≤ 0.4K), 500m (≥ 1.5K); Low noise mode 200m (≤ 0.4K), 300m (≤ 0.75K), 500m (≥ 1.5K).

All main circuit wires must pass through anti cutting sheaths (wiring covers for 22K and below models).

3.2 Control Circuit Wiring

The control circuit terminals are divided into: input signal, output signal, analog signal, and communication interface.

Input signal (24VDC optoelectronic isolation):

STF/STR: Forward/Reverse Start Signal.

RH/RM/RL: Multi speed selection (high/medium/low speed).

JOG: Jog mode selection.

RT: Second acceleration and deceleration time selection (simultaneously activating second torque boost, second V/F, etc.).

AU: Current input selection (4-20mA frequency command is valid).

MRS: Output stopped (immediately turn off the inverter pulse).

RES: Reset (clear protection in case of fault).

CS: Instant stop and restart selection (to be used in conjunction with Pr.57).

SD: Input common terminal (drain logic). The factory is designed for drain logic, and the jumper can be changed to switch to source logic.

Output signal (open collector electrode, 24VDC/0.1A):

RUN: Running signal (ON when frequency ≥ startup frequency).

SU: Arrival frequency signal (output frequency is ON within the range of ± Pr.41 of the set frequency).

OL: Overload alarm (ON when stall prevention is activated).

IPF: Instantaneous power outage/undervoltage signal.

FU: Output frequency detection (ON when frequency ≥ Pr.42 is set).

SE: Output common terminal.

Analog input:

10/10E: 5V/10V power supply (10mA) for frequency setting potentiometer.

2: Voltage frequency command (0-5V or 0-10V, input resistance 10k Ω).

4: Current frequency command (4-20mA, input resistance 250 Ω, AU signal ON required).

1: Auxiliary frequency input (± 5V or ± 10V, used for superposition or bias).

5: Simulate common terminal (not grounded).

Analog output:

FM: Pulse output (1440 pulses/second @ full range, calibratable), used for frequency meters.

AM: 0-10V analog output (configurable monitoring item).

PU interface (RS-485):

RJ45 socket, communication parameters up to 19200bps, maximum distance 500m, supports 1: N connection (up to 32 units). Pins 2 and 8 are 5V power supplies and are only for use on the operation panel. They should not be used for communication.

Notes:

The control line should use 0.75mm ² shielded twisted pair and be routed separately from the main circuit cable (distance ≥ 30cm).

Improving the control logic (drain/source) requires moving the jumper on the back of the control circuit terminal block and can only be operated when the power is off.

Operation panel and operating mode

FR-A500 comes standard with FR-DU04 simple operation panel and optional FR-PU04 full parameter unit. The panel consists of 5 buttons, 4 LED lights, and 5 status indicator lights.

4.1 Operating Mode

Set the operating mode through Pr.79 "Operation Mode Selection":

Description of Set Value Mode

When the power is turned on, the external mode can be switched to PU mode through the panel

The frequency and start stop of PU operation mode are completely controlled by the operation panel

The frequency of the external operating mode is set by an external potentiometer/4-20mA, and the start stop is controlled by terminals STF/STR (factory setting)

3 External/PU Combination Mode 1: The frequency is set by the panel, and the start stop is controlled by the terminal

4 External/PU Combination Mode 2 Frequency given by external, start stop controlled by panel FWD/REV key

5 program running modes automatically run according to the preset schedule (Pr.200-Pr.231 needs to be set)

During operation, it is possible to switch between PU, external, and communication modes

7 External mode (PU interlock) allows switching to PU mode when X12 signal is ON

8 external signal switching mode X16 signal selection external or PU mode

Pre startup inspection:

Confirm that the POWER light is on and there is no ALARM light.

After the first power on, parameter initialization (Pr.77=1 or parameter clearing) or factory reset should be performed, and then reset according to the application.

4.2 Frequency Setting and Monitoring

In PU mode, press the MODE key to enter the frequency setting mode, use the ▲/▼ keys to modify the frequency, and press the SET key for 1.5 seconds to write. In monitoring mode, it can cyclically display: output frequency → output current → output voltage → alarm history. The main display content (such as operating speed, motor torque, power, etc.) can be changed through Pr.52.

Guidelines for Setting Core Parameters

The FR-A500 has hundreds of parameters, and the following are the most commonly used and essential parameters that must be understood.

5.1 Basic parameters (Pr.0~Pr.9)

Parameter Name Typical Setting Range and Description

Pr.0 torque increases by 0-30%. Used to compensate for low-frequency voltage drop. The standard motor is about 2-6%, and excessive current may cause overcurrent.

Pr.1 maximum frequency 0~120Hz (can be extended to 400Hz, assuming Pr.18).

Pr.2 minimum frequency 0~120Hz. Output the minimum frequency even below this frequency (note motor heating).

Pr.3 The fundamental frequency is generally set to the motor nameplate frequency (50Hz or 60Hz).

Pr.4-6 multi-stage speed setting (high/medium/low) is selected through RH/RM/RL terminal combination.

Pr.7 acceleration time 0~3600s. The time required to accelerate from 0Hz to Pr.20 reference frequency.

Pr.8 has the same deceleration time as Pr.7.

Pr.9 electronic thermal overload relay sets the rated current of the motor (A). Protect the motor from overheating.

5.2 Acceleration, Deceleration, and Braking (Pr.10~Pr.16, Pr.30, Pr.70)

Pr.10 DC braking starting frequency: usually set to 3Hz. Pr.11 braking time (0.5-10s). Pr.12 braking voltage (0-30%).

Pr.15 jog frequency: factory 5Hz. Pr.16 jog acceleration and deceleration time.

Pr.30 regeneration function selection: 0=built-in brake (≤ 7.5K); 1=External high inertia braking resistor; 2=Connect FR-HC/FR-CV.

Pr.70 special regenerative braking duty cycle: set to 10% ED when combined with Pr.30=1.

5.3 Stall prevention and protection (Pr.22, Pr.23, Pr.66, Pr.156)

Pr.22 stall prevention action level: factory 150% (relative to rated current). During acceleration, deceleration, or constant speed, if the current exceeds this value, the frequency converter will automatically adjust the frequency to prevent overcurrent tripping.

Pr.156 Stall Prevention Action Selection: Actions for acceleration, constant speed, and deceleration can be set separately, and high response current limitation can be selected (high response limitation must be turned off for vertical lifting or it may stall and fall).

5.4 Advanced Control (Pr.80, Pr.81, Pr.89, Pr.96)

Pr.80 motor capacity (0.4~55kW) and Pr.81 motor pole number (2, 4, 6...): After setting, it automatically switches to advanced flux vector control, achieving 150% starting torque at 0.5Hz.

Pr.89 speed control gain: used to adjust the speed response when the load changes.

Pr.96 offline self-tuning:

Setting 1: No rotation setting (motor does not rotate), measure the motor constant.

Setting 101: Rotation setting (the motor runs at 60Hz for about 40 seconds) for higher accuracy. Mechanical safety must be ensured before setting.

After setting normally, Pr.96 displays "3" or "103", and if abnormal, it displays "9", etc.

5.5 Communication parameters (Pr.117~Pr.124, Pr.342)

Pr.117 communication station number: 0~31.

Pr.118 communication speed: 48/96/192 (hundred bps).

Pr.119 stop bit/data length: 1=data length 8, stop bit 2; 0=Data length 7.

Pr.120 parity check: 0=none, 1=odd check, 2=even check.

Pr.121 retry count: 9999 indicates no alarm in case of communication error.

Pr.122 Communication check interval: If 0 is not set and there is no communication after this time, an E.PUE alarm will be triggered.

Pr.342 E ² PROM write selection: 0=write to E ² PROM (limited lifespan), 1=write only to RAM (power loss).

5.6 Auxiliary Function Parameters

Pr.37 Speed Display: Set the speed coefficient to display the mechanical speed (r/min) on the panel.

Pr.52 main monitoring selection: Use 0 to display frequency, 6 to display motor speed, 23 to display cumulative operating hours, etc.

Pr.73 0-5V/0-10V selection: The polarity reversal or superposition function of terminal 1 can be enabled simultaneously.

Pr.79 Operation mode selection: detailed.

Pr.251 output phase loss protection: Set to 1 to enable phase loss shutdown protection.

Fault codes and troubleshooting process

The protection functions of FR-A500 are divided into: main fault (output cut-off), minor fault (displayed but not stopped), and warning (such as stall). Common fault codes and their solutions:

Main reasons and countermeasures for panel display name

E. OC1 acceleration overcurrent acceleration time is too short, motor cable short circuit, output side contactor action prolongs acceleration time, check output wiring

E. OC2 constant speed overcurrent load mutation, motor insulation damage reduces load variation, using advanced flux vector control

E. OV1 acceleration regeneration overvoltage accelerates too quickly, causing the motor to generate electricity (such as lifting and lowering acceleration), shortening the acceleration time, and installing a braking resistor

E. OV3 deceleration regeneration overvoltage deceleration time is too short, motor energy feedback is too large, prolonging deceleration time, choose braking unit

E. THM motor overload (electronic thermal relay) motor long-term overload reduces load, check Pr.9 setting

E. THT frequency converter overload output current exceeds 150% for more than 60 seconds. Check if the load is too large and increase the frequency converter capacity

E. IPF instantaneous power outage protection for power interruption>15ms, check the power supply, enable instantaneous stop and restart (Pr.57 ≠ 9999)

E. UVT undervoltage protection: The power supply voltage is too low, or the P-P1 short-circuit is not connected. Check the power supply and connect the short-circuit or DC reactor

E. FIN radiator overheating, high ambient temperature, fan failure, blocked heat sink. Clean the fan and improve ventilation

E. GF output side ground fault motor or cable short circuit to ground. Use a megohmmeter to check the motor insulation and replace the cable

E. LF output phase loss motor has a broken phase and loose terminal. Check the terminal U/V/W and set Pr.251=1 to enable protection

E. PUE PU connection disconnection or communication error operation panel or RS-485 communication interruption check the connection line and confirm Pr.75 setting

E. RET retry count exceeded the preset retry count and failed to successfully recover and eliminate the fundamental fault, then clear the alarm

Fault reset method:

Press the STOP/RESET button on the panel (in the fault state).

Connect the RES-SD external terminal for at least 0.1 seconds.

Turn off the power and then turn it back on (pay attention to the discharge time of the capacitor).

Daily maintenance and lifespan management

7.1 Regular inspection items

Part inspection content cycle

Abnormal noise and vibration of cooling fan, whether the fan stops running, daily auditory/annual replacement

The main circuit capacitor shell expands, leaks, and the capacitor capacity is below 80% of the rated value, which will be replaced in about 10 years

The contact resistance of the relay increases and the contacts adhere according to the number of switches

Loosening and discoloration of wiring terminal screws due to overheating should be re tightened annually

Dust accumulation and blockage on the heat sink, clean and blow clean monthly

Control circuit electrolytic capacitor bulging and dim display. Replace the entire board after 10 years

7.2 Insulation Resistance Test (Megohmmeter)

Only conduct a 500V megohm test on the main circuit (R, S, T, U, V, W to ground), and the insulation resistance should be ≥ 5M Ω. Before the test, all external wiring must be removed and the control circuit terminals must be short circuited (to prevent damage to electronic components from the test voltage).

It is strictly prohibited to conduct megohm testing on control circuit terminals, otherwise I/O will be permanently damaged.

7.3 Capacitor lifespan alarm

Pr.503 displays the cumulative running time (in 100 hours), and Pr.504 sets the alarm output threshold. When the accumulated time exceeds the set value, a replacement notice can be output through terminal Y95. The lifespan of a smoothing capacitor is approximately 87600 hours (10 years) in a typical environment (average annual temperature of 40 ℃).

Typical application debugging process

8.1 Standard fans/pumps (variable torque load)

Install and wire (main circuit R/S/T power supply, U/V/W to motor, control terminal STF/SD contact switch).

Parameter settings: Pr.14=1 (variable torque mode), Pr.1=50Hz, Pr.3=50Hz, Pr.7=20s, Pr.8=20s, Pr.9=motor rated current.

Select the external operation mode (Pr.79=2), connect the STF signal, slowly increase the frequency potentiometer, and observe the motor smoothly accelerating to 50Hz.

Enable energy-saving mode: Pr.60=4 (energy-saving mode), the frequency converter automatically optimizes the output voltage and reduces power consumption.

8.2 Vertical lifting (with mechanical braking)

Choose advanced flux vector control: Pr.80=motor capacity, Pr.81=number of poles.

Perform offline self-tuning (Pr.96=101).

Enable brake sequence function: Pr.60=7 (requires brake opening completion signal BRI), or Pr.60=8 (no confirmation signal required).

Set braking related parameters:

Pr.278 brake opening frequency (≈ 3Hz)

Pr.279 brake opening current (50-90% rated current)

Pr.280 brake opening current detection time (0.3s)

Pr.281 Braking action time upon startup (0.3s)

Pr.282 brake closing frequency (6-10Hz)

Allocate input terminals BRI (Pr.180-Pr.186 set to 15) and output terminals BOF (Pr.190-Pr.195 set to 20).

Wiring: BOF controls the brake contactor, BRI connects to the brake auxiliary contact. Ensure mechanical interlocking.

8.3 RS-485 Computer Communication

Hardware: Connect RJ45 (PU port) to RS-485 converter. When there are two or more units, use multi-point wiring and connect a 100 Ω terminal resistor in parallel at the farthest end.

Parameters: Pr.117=1 (station number), Pr.118=192, Pr.119=1, Pr.120=2 (even parity check), Pr.121=3，Pr.122=0.5s，Pr.123=0，Pr.124=2。

The host sends an instruction frame (format: ENQ station number instruction code data verification CRLF). Read and write frequency, start stop, monitor current/voltage, etc.