Delta MS300 Series User Manual page 464

 When you set Pr.14-74 or Pr.14-77 to 2 or 4, an ot3/ot4 warning displays and the drive stops
running after over-torque detection. The drive does not run until you manually reset it.
14-80
Electronic Thermal Relay Selection 3 (Motor 3)

14-82
Electronic Thermal Relay Selection 4 (Motor 4)

Settings
 Prevents self-cooled motor from overheating under low speed. Use an electronic thermal relay to
limit the drive's output power.
 Setting the parameter to 0 is suitable for an inverter motor (motor fan using an independent
power supply). For this kind of motor, there is no significant correlation between cooling capacity
and motor speed. Therefore, the action of electronic thermal relays remains stable in low speed
to ensure the load capability of the motor in low speed.
 Setting the parameter to 1 is suitable for standard motor (motor fan is fixed on the rotor shaft).
For this kind of motor, the cooling capacity is lower in low speed; therefore, the action of an
electronic thermal relay reduces the action time to ensure the life of motor.
 When the power is cycled frequently, if the power is switched OFF, the electronic thermal relay
protection is reset; therefore, even setting the parameter to 0 or 1 may not protect the motor
well. If there are several motors connected to one drive, install an electronic thermal relay in
each motor.
14-81
Electronic Thermal Relay Action Time 3 (Motor 3)

14-83
Electronic Thermal Relay Action Time 4 (Motor 4)

Settings
 Set the parameter to 150% of motor rated current and use with the setting of Pr.14-81 and Pr.14-
83 to prevent motor damage due to overheating. When it reaches the setting, the drive displays
"EoL3 / EoL4", and the motor coasts to stop.
 Use this parameter to set the action time of the electronic thermal relay. It works based on the I2t
characteristic curve of electronic thermal relay, the output frequency and current of the drive, and
0: Inverter motor (with external forced cooling)
1: Standard motor (motor with the fan on the shaft)
2: Disable
30.0–600.0 sec.
Chapter 12 Descriptions of Parameter SettingsMS300
455
Default: 2
Default: 60.0