Service manual

3. Electrical Parts
3-11
Adjusting V/Hz characteristic
If at the start stage of engine, voltage adjustment and stability adjustment have been already done,
it is not necessary to adjust the V/Hz characteristic. But if at no load operation any trouble of voltage
adjustment function occurs, or voltage disappears, adjust V/Hz characteristics, according the
following procedures.
1. TurnV/Hz characteristics volume knob(V.F.ADJ) fully clockwise. (Notching position ;10/10)
2. Start engine and adjust the frequency to 57Hz and then slowly turn V/Hz characteristic
volume knob (V>F>ADJ) counterclockwise to set it at the position of voltage drop approx. 1%
of the rated voltage ( see the table undermentioned).
Notching position of V/Hz characteristics volume (V.F.ADJ) : 3/10
Voltage
Frequency
240V 480V
57Hz 238V 475V
3.The frequency compensation characteristic and V/Hz corner frequency are shown in the
following table.
Frequency compensation
characteristics and V/Hz corne
r
Output voltage (%)
Corner frequency
100
80
60
40
20
0
20 40 60 80
Frequency (Hz)
60Hz