Parameter Details
11
11.9 L: Protection Functions
YASKAWA ELECTRIC SIEP C710617 05F YASKAWA AC Drive GA700 Technical Manual 939
11.9 L: Protection Functions
L parameters set the following functions.
• Motor Overload Protection
• Operation During Momentary Power Loss
• Stall Prevention
• Speed Detection
• Auto Restart
• Detection of Overtorque/Undertorque
• Torque Limit
• Hardware Protection
◆ L1: Motor Protection
L1 parameters set the motor overload protection function.
■ Motor Protection Using Positive Temperature Coefficient (PTC) Thermistors
The temperature resistance characteristics of three PTC thermistors in the motor stator winding protect the motor
from overheat.
The PTC thermistors must have the characteristics in motor 1 phase as shown in Figure 11.123.
Figure 11.123 PTC Thermistor Temperature and Resistance
When the PTC input signal input to the drive is more than the overload alarm level, the drive detects oH3 [Motor
Overheat (PTC Input)] and flashes it on the keypad. The drive continues the operation set in L1-03 [Motor
Thermistor oH Alarm Select].
The overheat fault level triggers an oH4 [Motor Overheat Fault (PTC Input)] fault, and outputs a fault signal. The
drive outputs a fault signal, and stops the motor with the stop method set in L1-04 [Motor Thermistor oH Fault
Select].
Note:
PTC is an acronym for Positive Temperature Coefficient.
Figure 11.124 shows the configuration procedure when you use terminal A3.
1. Connect the PTC thermistor input from the motor to analog input terminal A3 on the drive.
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