Protection Functions - Hitachi J300U Series Instruction Manual

8. PROTECTION FUNCTIONS

The J300 series inverters are equipped with protection functions against overcurrent,
overvoltage, and undervoltage which protect the inverter. If the protection functions are
engaged, the output is shut down, motor runs free and holds that condition until it is reset.
Description
Over current A currrent due to the alternating current CT between the power module
protection and output terminal {U(T1), V(T2), W(T3)} is detected.
When the motor is restricted or decelerated suddenly, a large current
flows through the inverter and causes a fault. Therefore, when an
abnormal current is detected by the alternating current CT and it exceeds
a specified value, the output is cut off. (An abnormal current is also
detected in the power module. Refer to
Overload
When a motor overload is detected by the electronic thermal function, the output
protection
of the inverter is cut off.
(NOTE 1)
Braking When the braking time exceeds the satting by
resistor overload overvoltage the output of the inverter is cut off.
Overvoltage When the converter voltage exceeds a certain level due to regenerative energy from
protection the motor, this protection function engages, and the output of inverter is cut off.
EEPROM error When the memory built in has problems due to noise or excessive temperature rise,
(NOTE 2) this protective function engages, and the output of inverter is cut off.
A decrease of the input voltage of an inverter results in improper function of the
Undervoltage
control circuit. It also generates motor heat and causes low torque. Output is cut off
protection
when the input voltage goes down to less than 150-160V/300-320V(200/400Vclass).
CT error Abnormality on built-in CT and the output of the inverter is cut off.
Malfunction or abnormality on built-in CPU and the output of the inverter is cut
CPU error
off.
An abnormality signal from external equipment cuts off the output of the inverter.
External trip
(When external trip function is selected)
It indicates an error when power is turned on while the inverter is being run.
USP error
(When USP function is selected)
Ground fault The inverter is protected by detection of ground faults between the inverter output
protection and the motor upon power on. There may be the possibility of power module failure.
When the input voltage is higher than the specified value, it is detected 100 seconds
after power is turned on and the output is cut off. However, when a voltage higher
Input overvoltage than approx. 250 to 270 V (200V class),
500 to 530 V (400 V class) is inputted, it is higher than the rated value of the part
in use, so that the part may not be protected and damaged.
When an instantaneous power failure for more than 15 ms occurs, the output is cut
Instantaneous
off. When the instantaneous power failure time is long, the fault signal is released.
power failure
Note that when restart is selected, the equipment restarts when the running
(NOTE 4)
command remains.
Contents
, , , and
braking duty factor, an
8-1
Display
Constant
speed
Dec.
Acc.
.)