YASKAWA GA800

12.9 L: Protection Functions
958 YASKAWA SIEPC71061737D GA800 Drive Technical Reference
12.9 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 thermistor must have the characteristics shown in Figure 12.119 for each motor phase.
Figure 12.119 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)]. The drive continues the operation set in L1-03 [Motor Thermistor oH Alarm Select]. By
factory default, oH3 flashes on the keypad and the drive continues operation.
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 uses the stop method set in L1-04 [Motor Thermistor oH Fault Select] to stop the
motor.
Note:
PTC is an acronym for Positive Temperature Coefficient.
Figure 12.120 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.