Thermistor Thermal Protection - Hitachi L100 Series Instruction Manual

4–20
Using Intelligent Input Terminals

Thermistor Thermal Protection

Motors that are equipped with a thermistor can be protected from overheating. Input
terminal [5] has the unique ability to sense a thermistor resistance. When the resistance
value of the thermistor connected to terminal [TH] (5) and [L] is more than 3 k Ohms
±10%, the inverter enters the Trip Mode, turns OFF the output to the motor, and
indicates the trip status E35. Use this function to protect the motor from overheating.
Option Terminal
Code Symbol
19 TH
Valid for inputs:
Required settings:
Notes:
•
Be sure the thermistor is connected to terminals [5]
and [L]. If the resistance is above the threshold the
inverter will trip. When the motor cools down
enough, the thermistor resistance will change
enough to permit you to clear the error. Press the
STOP/Reset key to clear the error.
Input
Function Name
State
Thermistor Thermal Sensor When a thermistor is connected to terminals [5]
Protection
Open
C_05 only
(none)
Description
and [L], the inverter checks for over-temperature
and will cause trip (E35) and turn OFF the
output to the motor
An open circuit in the thermistor causes a trip,
and the inverter turns OFF the output
(requires input configuration—
Example
see page
3–32):
TH
L 5 4 3
thermistor
MOTOR
See I/O specs on page 4–6.
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