HT Motor - Direction of Rotation

The direction of rotation of a motor is rather less significant than the direction of rotation of the equipment that the motor is driving, as anyone that has tried to obtain design performance from a centrifugal pump running backwards will readily acknowledge.

Ask the supplier. It is usually due to the direction of the cooling fan. If the fans are bidirectional (usually) then OK. But for many HT motors they don't do it, to improve the fan efficiency.

I agree, asking the manufacturer would be the correct source. (I'd be stunned if the motor was a single phase with a shaded pole. Thus making it spin only one way.) One simple possibility not mentioned is with such a high torque output the manufacturer wants the assembler to know the anticipated DOR with specified wiring to prevent mechanical damage.

sb makes the point of fan direction. I have also seen instances where the bearings are designed for specific direction, but this is also rare in emotors.

In addition it is common practice to order the driver (motor in this case) from the supplier of the driven machine (pump or blower) and the motor and its direction of rotation are specified by the driven equipment manufacturer.

Many customers insist on direction of rotation arrows on both the driver and the driven (I do).

We too and ask for double arrow in case of bi-directional (and that is along with rating plate RPM=1480 CW or 1480 CW/CCW

Is the HT a brand name? What does it stand for?

High Tension.

Don't ask why tension (it is already covered in one of the previous threads)

dear,

direction of rotation relates to the UVW PHASE SEQUENCE. this helps you in obtaiining the corrormally, HT motors are of very high horse power rating, with high torques. This improvestr the safety of the mechanical equipment coupled to the motor.

Hello Guest,

I would have thought it simply to be certain you are not making an error while connecting it?

If you run the driven equipment by mistake with wrong DOR, the eqpt may get damaged beyond repair. The DOR marking will help correct initial fit up without need to change DOR.

Another reason why manufacturers fit a uni-directional fan to motors (in addition to efficiency) is to reduce the noise level of the motor.

The uni-directional fan has lower noise levels compared to the bi-directional fan. These fans are normally fitted when a customer has a more stringent noise level specification to comply with and generally fitted to high speed motors (2 pole motors).

To prevent potential damage to the pump a commissioning process that is required for the company I work for; the pump is uncoupled and the motor is bump tested to clearly identify what direction the motor rotates. If the motor rotates wrong then the wiring configuration is changed.

It is sipmle you know for what types of electrical driving control, after conect the volte or power if the moter rotet not corect diraction you change the phase after that rotate the right diraction. one thing remamber all electrical moters are the same prinsip work.

The motor manufacturer does not know the application of the motor in the field.The factory designed rotation is indicated for informational purposes.Certain applications cannot tolerate a reversed rotation.A pump with a ratchet on the impeller comes to mind.The ratchet prevents backflow. If the rotation is wrong when you apply the juice, it will instantly destroy the motor and pump.

Other applications are more tolerant, and will not self destruct if you get it wrong.

Reversing the wiring lugs on a large motor is not easy, so it is best to get it right the first time.

Use a phase meter to identify the phases, and apply them according to your desired rotation

EZStreet