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Using Intelligent Input Terminals
Operations
and Monitoring
4–20
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
Code
Terminal
Symbol
Function Name
Input
State
Description
19 TH Thermistor Thermal
Protection
Sensor When a thermistor is connected to terminals [5]
and [L], the inverter checks for over-temperature
and will cause trip (E35) and turn OFF the
output to the motor
Open An open circuit in the thermistor causes a trip,
and the inverter turns OFF the output
Valid for inputs:
C_05 only
Required settings: (none)
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.
Example (requires input configuration—
see page
3–32):
12345L
P24
See I/O specs on page 4–6.
TH
thermistor
MOTOR