Delta MS300 Series User Manual page 465

Chapter 12 Descriptions of Parameter SettingsMS300
the operation time to prevent the motor from overheating.
 The action of the electronic thermal relay depends on the settings for Pr.14-80 and Pr.14-82
Pr.14-80 or Pr.14-82 is set to 0 (using inverter motor):
1.
When the output current of the drive is higher than 150% of the motor rated current (refer to
the motor rated current % corresponded to the motor rated frequency in the motor cooling
curve with independent fan), the drive starts to count the time. The electronic thermal relay
acts when the accumulated time exceeds Pr.14-81 or Pr.14-83.
Pr.14-80 or Pr.14-82 is set to 1 (using standard motor):
2.
When the output current of the drive is higher than 150% of the motor rated current (refer to
the motor rated current % corresponded to the motor rated frequency in the motor cooling
curve with shaft-fixed fan), the drive starts to count the time. The electronic thermal relay
acts when the accumulated time exceeds Pr.14-81 or Pr.14-83.
The actual electronic thermal relay action time adjusts according to the drive output current
(shown as the motor loading rate %). The action time is short when the current is high, and
the action time is long when the current is low. Refer to the following diagram.
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