Hi All,

Is there any simple circuit to identify the phase reverse or phase sequence change in a 3 phase (star connected) 440V system?

Thanks in advance

__________________
Sqn R.K. Chakravarthy
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Sky is not the limit for Air Warriors

 

Is there any other simple method, in addition to the one cited below to identify the phase reverse in 3 phase system.

Known method: Convert the sine to square using Zero crossing detector and then compare the rising time between the phase using a Micro controller.

__________________
Sqn R.K. Chakravarthy
----------------------
Sky is not the limit for Air Warriors

 

What do you want to prove !

The phase sequence is clockwise or anti-clockwise. The only time when a change may happen is when the cables get transposed when a transformer is replaced or a generator is inserted and appropiate before and after tests were not done.

Get a phasesequence meter ( for continuous duty ) with optical indicators and sense these with an optocoupler to detect rotation and trigger your alarm or relay.

Cheers, Raymond

__________________
There are more ways to get to Rome.

Electricity, Electric clocks, Meters and Trains are great.

 

Hi Rodalco,

I wanted to know , on what principle this stuff work? I have a blower in the workshop, which is driven by the 3phase motor. Some time the phase sequence get change(R Y B) due to other experiment done inside. This is making the blower to work as suction device. I wanted to sense the phase sequence and if the phases are not in the correct sequence ( ie RBY, YRB,BRY etc) , i need to de-energize the relay connected to the motor.

Could you please tell me , is there any other easy method to do this inaddition to the one i mentioned earlier ?

Thanks for your valuable guidance.

__________________
Sqn R.K. Chakravarthy
----------------------
Sky is not the limit for Air Warriors

 

A simple way would be 2 zero crossing detectors on the R & B phases. The R would trigger a 10mS monostable, if the B detector triggers before the monostable times out then the phases are wrong. Another very good indicator is a fan that runs backward.

How on earth do the phases get changed in the first place?

Mike.

 

Go to http://www.edn.com/archives/1998/042398/09di.htm
and scroll down to "$5 junk-box circuit determines phase sequence"