Delta Electronics VFD-G manual Momentary Power Loss Operation

Chapter 4 Parameters

The allowable power loss time must in the condition that AC drive auxiliary power is working normally. If auxiliary power is turned off in the allowable power loss time, the actual allowable power loss time will be shorter than the parameter setting.

08 - 06	Speed Search Time		Unit: 0.1
	Settings	0.1~5.0 Sec	Factory Setting: 0.5

This parameter determines the delay time from fault (power loss, OV, OC or BB) recovery to start to execute the function of speed search time.

08 - 07	Maximum Speed Search Current		Unit: 1
	Settings	30~150%	Factory Setting: 110

This parameter determines maximum current of speed search.

Maximum speed search current will have influence with synchronization attained time. The greater this parameter is set, the faster it will be synchronization. But if the parameter setting value is too great, it may occur over-loaded protection.

If 08-04 is set to 01: when speed search is from top downward, output frequency is searched from master frequency command downward. Now output voltage and output current will be added from zero. When output current is equal to 08-07 setting value, AC drive output current will retain in a fixed value and output frequency will keep on searching from top downward. When output frequency and output voltage is overlapped with V/f setting frequency, AC drive will judge that is synchronization attained and accelerates from V/f curve to master frequency command.

If 08-04 is set to 02: AC drive will accelerate according to V/f curve and won’t do any special treatment.

	Maximum allowable					Max. Allowable
	power loss time					Power Loss Time
Power	08-05					08-05
Input					Speed
			Speed Search		Synchronization
					Detection
	08-04=01			08-04=02
Output		B.B. Time					B.B.Time
Frequency	08-06			08-06
Output
Voltage

Momentary Power Loss Operation

4-64 Revision July 2008, EG03, SW V1.06