YASKAWA GA700 Series

Parameter Details
12
12.9 L: Protection Functions
YASKAWA SIEPC71061705H GA700 Series Technical Manual 871
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 12.122 for each motor phase.
Figure 12.122 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 12.123 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.
Figure 12.123 Connect Motor PTC
2. Set drive DIP switch S1-3 to V (voltage) and set DIP switch S4 to PTC.