# 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

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 – user16307 May 8 '15 at 0:05
• we measure more than 1000 rpm like 1160 rpm. How can it be possible? – user16307 May 8 '15 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 – JonRB May 8 '15 at 0:10
• no it is 50hz in europe – user16307 May 8 '15 at 0:11
• we use a vfd but vfd cannot increase motor speed more than its synchronous speed right? – user16307 May 8 '15 at 0:11