Hitachi RAM-90QH5, Service Manual, Page: 57 / 83

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6. Overload control circuit (OVL control circuit)
Judgement value according to the rotation speed
(internal judgement value)
External judgement value
Detection
resistor
Translation
(R503)
DC current
Rotation speed data
To power module
negative
terminal
Primary
CT
0V
0V
Voltage amp.
circuit
Judgement OVL
with respect to
externally set
value
Judgement OVL
according to the rotation
speed
A/D
converter
OVL start current data
Selects data according
to the rotation speed and
DC voltage.
RC filter circuit
(Internal judgement)
DC voltage
DC
current
Rotation speed
Motor control
process
A/D
converter
A/D
converter
micro computer
Fig. 6-1 Overload Control System Configuration
Fig. 6-2