Baldor VS1MD instruction manual Example Speed search during Instant Power Failure restart

Example

Speed search during Instant Power Failure restart

•When the￿input power is cut off￿￿￿due to￿￿￿￿instant power failure, the inverter outputs Low voltage trip (LV) to hold the output.

•When the power is restored, the inverter outputs the frequency before the low voltage trip and the voltage is increased due to PI control.

•t1: If current is increasing over the preset level in H23, the rise in voltage will stop and the frequency is decreased.

•t2: If the opposite of t1 occurs, the increase in voltage starts again and the decrease in frequency stops.

•When the frequency and voltage are restored back to the nominal level,￿￿￿acceleration￿￿￿￿￿￿￿￿￿￿will continue at the frequency before trip.￿￿￿

Speed search operation is suitable for loads with high inertia. Stop the motor and restart when friction in load is high.

VS1MD keeps normal operation when instant power failure occurs and power is restored in 15msec for the use of its inverter rating.

Inverter DC link voltage can vary depending on output load quantity. Therefore, Low Voltage trip may occur when instant power failure is maintained over 15msec or output is higher than its rating.

Instant power failure specification is applied when input voltage to Inverter is 200 to 230V AC for 200V class, or 380 to 480V AC for 400V class.

8-16 VS1-MD AC Drive User Manual