Motor Overheat Protection Using Ptc Thermistor Inputs - Omron VARISPEED E7 User Manual

Motor Overheat Protection Using PTC Thermistor Inputs

This function provides a motor overheating protection using a thermistor (PTC characteristic – Positive Tem-
perature Coefficient) that is built into the windings of each motor phase.
Related Parameters
Parameter
Number
L1-03 Alarm operation selection during motor overheating
L1-04 Motor overheating operation selection
L1-05 Motor temperature input filter time constant
PTC Thermistor Characteristics
The following diagram shows the characteristics of the PTC thermistor temperature to the resistance value.
The shown resistance value is for one motor phase. Normally the 3 resistors (1 for each phase) are connected
in series
Resistance (Ohms)
Fig 6.30 PTC Thermistor Temperature-Resistance Value Characteristics
Name
Class F Class H
Tr: Temperature threshold value
Temperature
Machine Protection
Change
Setting Factory
during
Range Setting
Operation
0 to 3 3 No
0 to 2 1 No
0.00 to
0.20 sec. No
10.00
Access
Level
A
A
A
6-35