epzp02.pdf

MITSUBISHI ELECTRIC

NAGOYA WORKS

INVERTER ENGINEERING SECTION

TECHNICAL SHEET

P-ZP-02

OVER VOLTAGE STALL PREVENTION AND OL OPERATION

When the motor is decelerated with an inverter, regenerative energy flows into the inverter from the

motor and the DC bus voltage inside the inverter increase. When the DC bus voltage exceeds a

certain voltage level, the inverter performs an operation called the over voltage stall prevention to

prevent over voltage. This over voltage stall prevention and conditions for it are explained as follow.

1. Operation

When the motor is decelerated with an inverter, the motor behaves as a generator and

regenerative energy is sent back to the inverter. When the regenerative energy is substantial, the

main circuit's DC voltage inside the inverter increases. When DC voltage exceeds a certain

voltage level, the inverter falls into an over voltage trip to prevent damages to the inverter.

Therefore, the over voltage stall prevention operation is performed to avoid the over voltage trip.

This operation interrupts the deceleration process when the DC voltage exceeds a set voltage by

holding the output frequency at constant until the voltage decreases enough before restarting the

deceleration process. The operation to suppress the over voltage trip is performed as described

above.

2. Display at the operation

At the operation of the over voltage stall prevention, the monitor is displayed as follows:

Operation

Monitor display

Over voltage stall prevention

operation

Over current stall prevention

operation

Over voltage stall prevention

operation+ Over current stall

prevention operation

The OL signal which can be allocated to one of the output terminal is turned ON at the over

voltage stall prevention operation. It also turns ON during the overcurrent stall prevention

operation (there is no distinction of the ON terminal between overvoltage and overcurrent stall

prevention operations).

3. Conditions for operation

The over voltage stall prevention operates only when the voltage is increasing at deceleration and

does not operate when the voltage is increasing at constant speed or at acceleration. The

operation voltage level is set according to the model type and cannot be changed. (When the

regenerative control unit such as a built-in brake unit is installed, the built-in brake unit will

operate first because the operating voltage of the built-in brake unit is lower.)

Operation voltage list

Model type

DC bus voltage when

operation starts

DC bus voltage when

operation finishes

FR-A520 22K or smaller

Approx. 390V

Approx. 385V

FR-A520 30Kor greater

Approx. 385V

Approx. 380V

FR-A540 all capacity

Approx. 790V

Approx. 780V

FR-E500 series

Approx. 400V

Approx. 395V

The over voltage stall prevention operation can be disable by a parameter setting. When Pr. 156

set so as not to perform the over voltage stall prevention operation at deceleration, the over

voltage stall prevention operation will not be perform. Please note that the over current stall

prevention operation during deceleration is also disabled by the same setting.

INVERTER TECHNICAL SHEET : E(P-ZP-02)

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