# How to determine the pole number or synchronous speed of an AC motor from its rated RPM?

Trying to to determine the pole number or synchronous speed of the following AC motor from its rated RPM. Here are the details:

http://www.vanbodegraven.nl/en/products/ac-motors/asea-mbg-200-m-60-6/

What is its synchronous speed(stator winding frequency) and pole number?

A VFD is being used

• This question is closely related to electronics.stackexchange.com/questions/161956/… . May 8, 2015 at 3:51
• -1. The important fact that a VFD is in use was not mentioned in the question.
– user16324
May 8, 2015 at 9:40

Here is a table that has been useful to me in the past: -

Please also note that the motor you have linked is a standard induction motor and won't run at synchronous speed. It's likely to be a 6 pole machine running at 50Hz that would produce a synchronous speed of 1000 RPM. However there are a few other options that could be close but, as 50Hz is a standard frequency I suggest it is a 6 pole machine.

This appears to be an Induction machine for the European market & a 3pole pair machine.

Justification?

1) referring to 380Δ connection, url is netherlands, dialcode is +31 => 50Hz AC

2) the RPM listed is 970rpm. the peak operating point of an induction machine is just below the equivalent electrical sync speed. 50Hz for a single pole machine equates to 3000rpm. 1000rpm would be the closest integer divisor

• can I open chat with you May 8, 2015 at 0:05
• we measure more than 1000 rpm like 1160 rpm. How can it be possible? May 8, 2015 at 0:07
• sounds like you hooked it upto 60Hz. 60Hz 3pole pair would have an electrical SYNC speed of 1200rpm ==> around 1100 taking into account the induction machine & slip
– user16222
May 8, 2015 at 0:10
• no it is 50hz in europe May 8, 2015 at 0:11
• we use a vfd but vfd cannot increase motor speed more than its synchronous speed right? May 8, 2015 at 0:11