Vacuum Starter Overload Heaters
Heater Selection
Select heaters based on motor nameplate full-load current. Tables are for continuous rated motors. Full-load current for a given horsepower motor will vary from one manufacturer to another and will depend on RPM of motor.
Type of Protection
Heaters selected directly from the tables provide a maximum of 125% protection at 400C ambient, is suitable for motors with a 1.15 service factor with a 400C rise or less and with motor and controller at the same temperature. For motors with 1.0 service factor or with a temperature rise greater than 400C without service factor rating, use one size smaller heaters than in table. The ultimate trip of the heater is approximately 125% of the minimum current shown in the tables in a 400C ambient. The overload relay provides protection in accordance with UL Class 20. For further data refer to Controlog section B.
Ambient Correction
Not necessary when overload relay is ambient compensated as identified by green reset rod. For control at an ambient constantly less than the motor ambient, correct by decreasing the nameplate motor
full-load current by 8% per 100C difference in ambient. For control at an ambient constantly greater than the motor ambient, correct by increasing the nameplate motor full-load current by 8% per 100C difference in ambient.
Branch Circuit Protection
Branch circuit protection should be provided per USA National Electric Code or the Canadian Electrical Code. Current rating of the protective device must not exceed the maximum value listed in the table.
Automatic Reset
Automatic reset operation should not be used with two-wire control
TO ORDER
* Consult Customer Service for price and availability.
* The charts below will provide assistance in identifying the correct overload heater for your application.
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