Hitachi SJ700-2 instruction manual Commercial power source switching CS function

Sample connection diagram and timing charts for

commercial power supply switching MC2

Related code

b003: Retry wait time before motor restart

b007: Restart frequency threshold

C001 to C008: Terminal [1] to [8] functions

Chapter 4 Explanation of Functions

(Example 3) Restarting with active matching frequency		After the retry wait time (b003), the
		inverter restarts the motor with the
FW		frequency set as "b030". The inverter
		subsequently decelerates the motor
		according to the setting of "b029"
FRS		while maintaining the output current
	b028	at the level specified for "b029".
Output current		When the output voltage matches
		the frequency, the inverter
	Deceleration according to	re-accelerates the motor up to the
	the setting of "b029"	frequency that was set when the
Inverter output		inverter shut off the output to the
		motor before the restart.
frequency	Frequency selected as the	If the inverter trips because of
		overcurrent when it restarts the
	setting of "b030"
		motor with input frequency, reduce
Motor speed		the setting of "b028".

b003

4.2.48 Commercial power source switching (CS) function

The commercial power source switching function allows you to switch the power supply (between the inverter and commercial power supply) to your system of which the load causes a considerable moment of inertia. You can use the inverter to accelerate and decelerate the motor in the system and the commercial power supply to drive the motor for constant-speed operation.

To use this function, assign function "14" (CS) to one of the terminal [1] to [8] functions (C001 to C008). When the CS terminal is turned off with an operation command being input, the inverter waits for the retry wait time before motor restart (b003), adjusts the output frequency to the speed of the free-running motor, and then accelerates the motor with the adjusted frequency. (The start mode is the starting with matching frequency.) However, the inverter may start the motor with 0 Hz if:

1)the motor speed is no more than half the base frequency or

2)the voltage induced on the motor is attenuated quickly.

3)If the motor speed falls to the restart frequency threshold (b007), the inverter will start the motor with 0 Hz. (See Section 4.2.27.)

Remark) Mechanically interlock the MC3 and MC2 contacts with each other. Otherwise you may damage the drive.

If the earth-leakage breaker (ELB) trips because of a ground fault, the commercial power will be disabled. Therefore, connect a backup power supply from the commercial power line circuit (ELBC) to your system if

needed.

Use weak-current type relays for FWY, RVY, and CSY. The figures below show the sequence and timing of operations for reference.

If the inverter trips because of overcurrent	NFB	ELBC		MC1		MC3	THRY
when it starts the motor with matching				R	U		Motor
frequency, increase the retry wait time				S	V
before motor restart (b003).				T	W
				R0
For circuit connections and switching
				T0
operations, see the sample connection
				H
diagram and timing charts for commercial
				O
power supply switching as shown on the
				L	AL1
right.
					AL2
The inverter can be set up so that it will				FW
					AL0
automatically retry operation at power-on.			FWY	RV
In such cases, the CS terminal (signal)			RVY	CS
shown in the figures below is not required.			CSY	CM1
For details, see the explanation of the
reset (RS) function (4.2.29).

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