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

Function Name

Input

 

 

 

 

 

 

Description

Code

Symbol

State

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

19

TH

Thermistor Thermal

Sensor

When a thermistor is connected to terminals [5]

 

 

Protection

 

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

 

Example (requires input configuration—

 

 

 

 

see page 3–32):

Required settings:

(none)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TH

Notes:

 

 

 

 

 

 

 

 

• Be sure the thermistor is connected to terminals [5]

 

L

5

4

3

2

1

P24

 

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.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

thermistor

 

 

 

 

 

 

MOTOR

 

 

 

 

See I/O specs on page 4–6.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Operations and Monitoring