Hitachi X200 Series instruction manual Group Fine Tuning Functions, Automatic Restart Mode

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“B” Group: Fine Tuning Functions

Configuring Drive Parameters

The “B” Group of functions and parameters adjust some of the more subtle but useful aspects of motor control and system configuration.

Automatic Restart Mode

The restart mode determines how the inverter will resume operation after a fault causes a trip event. The four options provide advantages for your applications. Frequency matching allows the inverter to read the motor speed by virtue of its residual magnetic flux and restart the output at the corresponding frequency. The inverter can attempt a restart a certain number of times depending on the particular trip event:

•Over-current trip, restart up to 3 times

•Over-voltage trip, restart up to 3 times

•Under-voltage trip, restarts up to 16 time

When the inverter reaches the maximum number of restarts (3 or 16), you must power cycle the inverter to reset its operation.

Other parameters specify the allowable under-voltage level and the delay time before restarting. The proper settings depend on the typical fault conditions for your application, the necessity of restarting the process in unattended situations, and whether restarting is always say.

<Example>

Power failure < allowable power fail time(B022), Inverter resumes

Input power

Inverter output

Freq. Pull-in restart level B030

Motor
current
Motor
rotation	Free-running
		Power fail	B029
Allowable power	B002		Freq. Pull-in restart
fail time
			Deceleration constant
Retry wait time		B003

If the actual power fail time is shorter than the B002 set value, inverter resumes from the set frequency in B011.

The resuming mode is called “frequency pull-in” and the inverter performs reduced voltage start to avoid overcurrent trip.

If the motor current exceeds the B030 set value during this period, inverter decelerates according to the B029 set value and helps to reduce the motor current.

And when the motor current is less than the B030, inverter increases the motor speed again. The performance continues this retry action until the motor speed comes to the previous set speed.

Overload restriction (B021~B028) is not valid when frequency pull-in is activated.

If the actual power fail time is longer than the B002 set value, the inverter does not resume and the motor will coast to stop.