Reversing Direction of Rotation on TEFC Motors

Reversing Direction of Rotation on TEFC Motors

Question: What is the procedure to follow when changing the direction of rotation on TEFC motors?

Answer: U.S. Electrical Motors’ TEFC motors are equipped with one of three types of external cooling fans:

1.) Propeller type (most two pole and some smaller motors)

2.) Sirocco type (most four pole motors)

3.) Radial type (some two and four pole motors; all six pole and slower motors)

Radial type fans are bi-directional. However, propeller and sirocco types are uni-directional. Although changing the rotational direction of a motor equipped with a propeller type requires a different fan, the sirocco type can be reversed in the field by performing the following steps:

1.) Remove the fan cover guard in order to gain access to the fan.

2.) Remove the fan from the shaft. This may require heating the fan hub to expand it loose from the shaft.

3.) Remove the "baffle plate" from the fan casting and mount it on the opposite side. This will require drilling and tapping new mounting holes (use the "baffle plate" as a template).

4.) Re-balance the reworked fan assembly.

5.) Install the fan back onto the shaft with the "baffle plate" toward the motor.

6.) Reinstall the fan cover guard.

7.) Remove any direction of rotation arrow(s), turn 180 degrees and reinstall.

8.) Reverse the leads if required to obtain the desired direction of rotation.

NOTE: Be sure the power is off and steps are taken to prevent accidental restarting of the motor before attempting to do any of the above procedures.

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