delta/star

[SAMER]

hi

in fact i have two question:

1)for a small evaporator 3 phase star/delta connection, to keep maximum air flow we connect the motor as star or delta?

 

2)when you close main duct dumper to reduce C.F.M for DX units, evaporator motor ampere will increase, decrease or no change?

[johnbose]

Depending on the inertia of the Fan, it may be difficult to start the motor in delta as starting currents can remain high for longer times. The manufacturer / supplier must have envisaged normal operation in delta, . MAx CFM is expected in delta.

For any fan with damper in duct, closing of damper will reduce the load on the fan and thus the motor

[GGOSS]

Great reply johnbose. Both accurate and to the point.

 

Keep up the good work.

 

Regards,

GGOSS

[petronila]

hello Sammer,

 

About your first question:

 

If you have a D/Y Three Phase Motor this motor could be connected at both voltages, then you have to use the right connection for the main voltage. Example: 220/400 Volts the 220 Connection is DELTA and the 400 V is Star.Refer to the name plate.

 

Regards

 

Petronila

[SAMER]

HI Johnbose

I think when you close the damper to reduce the CFM that's mean there is obstacle resist the air flow this cause more difficulty for the motor to pass the air that's mean load increase on the motor so current should be increased.

What's your opinion?

[GGOSS]

Hello Samer,

 

When the damper is closed there is no movement of air and therefore there is no load.

 

Regards,

GGOSS