Emb Overload - Trane TR200 Operating Instructions Manual

Electromechanical Bypass (EMB) Operation

EMB Overload

General Information
The overload device provides overcurrent protection for the motor when running in bypass. The thermally ac-
tivated overload monitors motor current and trips to remove power to the motor if a sustained overcurrent
condition exists. A Class 20 overload is standard with a variable setting for motor current. Test and reset buttons
are also provided. In drive mode, the drive provides current sensing and trip protection. Fuses provide quick
action for high over current conditions.
Prior to Enabling Overload
• Verify that the overload current dial setting matches the motor FLA rating on the motor nameplate.
• If the motor FLA is greater or less than range of the current dial, reconfirm that the motor hp and voltage
are within the option panel (and drive) rating. If less than the FLA rating, replace the overload with
the correct size. If greater than the FLA rating, replace the panel with one of a proper rating.
NOTICE
CAUTION MOTOR DAMAGE! REPEATED ATTEMPTS TO RESET OVERLOAD CAN CAUSE MOTOR DAMAGE. COR-
RECT OVERLOAD CONDITION AND LET OVERLOAD AND MOTOR RETURN TO NORMAL OPERATING TEMPERA-
TURE BEFORE RESETTING. SEE MOTOR MANUFACTURER'S RECOMMENDATIONS FOR TIME BETWEEN START
ATTEMPTS. FAILURE TO CORRECT OVERLOAD CONDITION AND LET MOTOR RETURN TO NORMAL OPERATING
TEMPERATURE COULD CAUSE MOTOR DAMAGE.
Operation
Overloads are rated by class. The class is defined by the NEC to determine the maximum time to trip. A Class
20 overload, for example, has a typical trip delay of 20 seconds or less at 600% current and normal operating
temperature. This allows for high motor inrush current for 20 seconds while the motor is ramping up to syn-
chronous speed. The trip time, however, is based on the percentage of overload. The higher the overload, the
shorter the trip time. It is important that the overload class not exceed the motor class rating or motor damage
could occur. For dual motor operation, an overload is provided for each motor. For contact motor select, one
overload is provided and monitors either motor when selected.
Overload Function Setup
• Set the overload current dial to the FLA of the motor. DO NOT add the service factor of the motor into
the setting. A service factor of 120% for Class 20 is designed into the overload.
• Pressing the test pushbutton verifies the operation of the overload. The overload should trip when
pressed. Use the reset pushbutton to reset the overload after test.
• Reset is used to reset the overload after it trips. If the overload is still hot, wait until the motor reaches
normal operating temperature before resetting. The overload offers a manual (hand) or auto reset
selection. It is highly recommended to operate in the manual factory setting to prevent the risk of
damage to the motor.
Illustration 5.5: Sample Overload Device
36
TRIP
MANUAL
AUTO
TEST
RESET
98NO 95NC
97NO 96NC
T1 T2 T3
TR200 Option Panel Operating Instructions