Protective Function - Hitachi FSG Series Service Manual

3.1.5.

PROTECTIVE FUNCTION

n Excessive High or Low Voltage for Inverter
a. Level of Detection
1. When the voltage of direct current is greater than
750V, abnormalities are detected.
2. When the voltage of direct current is smaller than
350V, abnormalities are detected.
b. Function
When abnormalities are detected, the inverter
compressor is stopped and transmit the signal code of
stoppage cause to PCB1.
c. Cancellation of Protection Function Transmission for
signal code of stoppage cause is cancelled when a
stopping order is given or main power source is cut off.
n Abnormality of Current Sensor
a. Level of Detection
When current of the inverter compressor decreases lower
than 0.5 A during the inverter compressor frequency
between 15Hz and 18Hz, an abnormality is detected.
b. Function When abnormalities are detected, the inverter
compressor is stopped, and transmit the signal code of
stoppage cause to PCB1.
c. Cancellation of Protection Function Transmission for
signal code of stoppage cause is cancelled when a
stopping order is issued or main power source is cut off.
n Overcurrent Protection for Inverter
a. Level of Detection
1. When the current detected by current sensor reaches
150% of the rated current, overcurrent is detected.
(Instantaneous Overcurrent)
2. When the current detected by current sensor exceeds
105% of the rated current continuously for 30 seconds
or for 3.5 minutes in total during a 10 minutes period,
overcurrent is detected. (Electric Thermal Relay)
b. Function
When abnormalities are detected, the inverter
compressor is stopped and transmit the signal code of
stoppage cause to PCB1.
c. Cancellation of Protection Function Transmission for
signal code of stoppage cause is canceled by stopping
order is issued or main power source is cut off.
n Protection of Transistor Module
a. Level of Detection
1. When some of the output terminals between "U" and
"V", "V" and "W", "W" and "U" of transistor module are
short-circuited, an abnormality is detected.
2. When the running current of transistor module
reaches (Maximum Rated Current 3 105%), an
abnormality is detected.
3. When an internal temperature is measured by internal
thermistor of transistor module exceeds 150°C, an
abnormality is detected.
4. When the control voltage of transistor module
decreases to 12.5V, an abnormality is detected.
b. Function
When abnormalities are detected, the inverter
compressor is stopped and the signal code of stoppage
cause is transmitted to PCB1.
c. Cancellation of Protection Function Transmission for
signal code of stoppage cause is canceled when a
stopping order is issued or main power source is cut off.
n Overload Control
a. Level of Detection
When the output current exceeds 105% of the maximum
output current, an abnormality is detected.
b. Function
An overload signal is issued when output current exceeds
105% of the maximum output current, and the frequency
decreases at a rate of 0.5Hz/s. For 10 seconds after the
output current decreases lower than 88% of the rated
current, the operation is performed with the compressor
frequency limited to the upper level frequency when the
output current decreases lower than 88% of the rated
one. However, if the frequency order is smaller than the
maximum value, the operation is performed according to
the order.
c. Cancellation of Protection Function After the operation
described in the above item b. is performed for 10
seconds, this control is canceled.
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