Electronic Motor Thermal Protection; Motor Thermal Protection Using Thermistor - Hitachi P1 Basic Instruction Manual

ELECTRONIC MOTOR THERMAL PROTECTION

The VFD has a built-in electronic motor thermal protection function and is configured for constant torque loading. When the output
current exceeds the value in bC110 for a calculated time based on frequency, time and a reduction ratio. The electronic thermal
protection function also has the ability to save the current data and calculate it based on output current and time.
Function
Electronic thermal level
Electronic thermal subtraction function
Electronic thermal subtraction time
Electronic thermal counter memory function

MOTOR THERMAL PROTECTION USING THERMISTOR

The temperature protection of an external device can be made by connecting a thermistor installed in the motor or other external
device to the inverter and setting the function of the thermistor. The external thermistor should be wired between the control
terminals TH+ and TH-. Set the thermistor selection [Cb-40] and the resistance level to cause an error [bb-70] in accordance with the
thermistor's specifications. When [Cb-40] is set to 02, [dA-38] motor temperature monitor indicates the detected temperature of the
motor.
[E035] thermistor error occurs when the thermistor resistance reaches the thermistor error level [bb-70] depending on the motor
temperature.
To use this function, the wiring distance between the motor and the inverter should be 20 m or shorter. Since the current flowing in
the thermistor is very weak, a measure such as wiring separation should be taken to prevent noise from the motor current.
When [Cb-40] is set to a value other than 02 NTC negative temperature coefficient resistor, [dA-38] motor temperature monitor
indicates 0 °C.
Function
Thermistor error level
Thermistor selection
Thermistor gain adjustment
Motor temperature monitor
Parameters
bC110
bC112
bC113
bC-14
Parameters
bb-70
Cb-40
Cb-40
dA-38
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Value
Motor FLA * 1.25
0 = disabled
1 = enabled
600 sec
0 = disabled
1 = enabled
Value
0 ~ 10000 ohms
0 = disabled
1 = PTC
2 = NTC
0.0 ~ 1000
-20.0 ~ 200.0 °C