MITSUBISHI ELECTRIC FR-D700 Inverter Complete Guide

Communication parameters: Pr.117~Pr.124 (station number, speed, data bit, stop bit, parity check, etc.).

If the operation and frequency are remotely controlled through RS-485, do I need to set Pr.79=1 (external operation mode) or Pr.79=2 (PU operation mode)? In fact, remote communication usually sets Pr.79 to 0 or 1, and cooperates with Pr.338~Pr.339, etc. Clearer: Set Pr.79 to 0 (combination mode) and select the communication operation command (Pr.338=1) and communication frequency command (Pr.339=1).

Troubleshooting: Communication timeout (E.PUE). Check the polarity of the wiring (+corresponds to SDA, - corresponds to SDB), confirm that the station number is consistent, and the communication speed matches. Quickly locate using the "Communication Test" function of FR Configurator software.

6.2 PC Software FR Configurator

By connecting the PC and frequency converter through RS-485, the FR Configurator (SW3-SETUP-WE) provides guided parameter setting, monitoring, graphical data (waveform display), and program conversion functions - it can easily convert the parameter files of the old FR-S500 series to FR-D700 format with just one click, greatly simplifying the upgrade and replacement work.

Practical tip: Use the "Batch Copy" function to save the parameters of a debugged frequency converter to a PC, and then write them to other frequency converters in the same batch to ensure consistency. It is also possible to store up to 3 sets of parameters and copy them offline through parameter unit FR-PU07 (supporting 8 languages).

Key points for selecting and installing peripheral devices

7.1 Circuit breakers and contactors

Input side circuit breaker: Select according to the input current of the frequency converter, refer to the rated table (such as FR-D720-2.2K using 15A MCCB). For the North American market, Class T fuses or UL489 circuit breakers are required.

Input side contactor: used for emergency power cut-off or maintenance isolation, but prohibits frequent start stop (switch life is about 1 million times). If frequent start stop is required, control terminals STF/STR should be used.

Output side contactor: Switching is only allowed when both the frequency converter and motor are stopped (such as power frequency standby switching). Cutting off the output during operation will cause overcurrent tripping.

7.2 Reactors and Filters

AC Reactor FR-HAL: It is recommended to install when the capacity of the power transformer is greater than 500kVA or when harmonic suppression is required. For single-phase 100V input and transformer ≥ 50kVA, an AC reactor must be installed to prevent surge overvoltage.

DC Reactor FR-HEL: Connect between P1 and P/+terminals (short-circuit wire needs to be removed). Used for power factor improvement and harmonic suppression.

EMC filter: In order to comply with EN61800-3 C3 category (second environment), SF series filters can be selected. The FR-D700-042 model has a built-in C2 level filter (restricted distribution in the first environment), with a maximum motor cable length of 10m.

Noise filter FR-BIF (H): for radio interference, installed on the input side.

Line noise filter FR-BSF01: used to reduce sensor misoperation, can be installed on the output cable.

7.3 Selection of Braking Resistors

Taking FR-D720-2.2K (R2 chassis) as an example: the minimum allowable resistance value Rmin is 19.5 Ω, the maximum resistance value Rmax is 47.1 Ω, the continuous braking power PBRcont is 2.2kW, and the maximum braking power PBRmax is 3.3kW (1 minute/10 minutes). When selecting MRS or MYS type resistors, their resistance value must fall between Rmin and Rmax, and the power must not be less than the actual braking energy. If a high load braking resistor FR-ABR is used, the duty cycle can be increased to 10% ED.

Calculation example: The load has a large inertia and needs to brake for 5 seconds every 20 seconds. The average braking power is equal to the actual peak power multiplied by (5/20). Ensure that the average value is less than PBRcont and the peak value is less than PBRmax.

Fault prompt: When the resistor is overheated or damaged, the frequency converter may report "E.OV" (regenerative overvoltage) or "E.bE" (abnormal brake transistor). The latter requires immediate power outage and replacement of the frequency converter.

7.4 Wiring precautions

The control circuit terminals use spring clip terminals, which do not require a screwdriver to tighten and are reliably crimped. However, when disassembling, a small flat head screwdriver is needed to press down on the release hole.

The main circuit terminal is a screw terminal, and it is recommended to use a flexible wire with insulated terminals, with a torque of the specified value (about 0.8~1.2N · m).

The output terminals U/V/W of the frequency converter must not be connected to the power supply, otherwise it will be immediately damaged.

The signal cable and power cable should be separated by at least 10cm, and the shielding layer should be grounded at one end (terminal 5). Do not form a loop by grounding the outer shell.

When the length of the motor cable is too long (exceeding 50m), leakage current caused by distributed capacitance may cause thermal relay misoperation. It is recommended to use Pr.9 electronic thermal relay instead of external thermal relay or reduce the carrier frequency (Pr.72).