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Relay-based solution to phase failure in 3-phase motor

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modeonz

modeonz

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in the 3 phase motor , if u change the connection of 2 phases the motor will rotate in the other direction .

so if the main supply had a fault and the operator change 2 phases wrongly , it will be very bad mistake .

is there is any relay which can detect this fault and control it


i know we can prevent this problem by using a microcontroller and " converter and inverter " circuites .

but i look for a solution by using the relays

can anyone help ?!!
 

important details of phase failure switch

Hello,

you can use a phase sequence monitor relay. This is a common part in industrial automation, should be available from serveral manufacturers. See the types from ABB for reference:
**broken link removed**

Regards,
Frank
 

phase failure

i read the manual . i see that this relay can monitor the phase sequence failure and then deenergize .

but if there is any relay that can correct the phase

i think if it can monitor the failure abd the yellow led switch on , it can exchange the phases with each other until it detect that it is correct so by this way it can correct it

i don't know if this is idea wrong or good

and finaly thanks for help
 

phase failure switch

I thought the possible usage would be obvious. You either can use it as montoring device, e. g. locking motor start in case of phase loss or phase reversal, or you can use it in cojunction with power contactors for automatic phase reversal. I used this technique with mobile machinery.
 

Re: q : phase failure

your idea is a good idea but i have a question to make it more clear

this relay monitor the change in the phase and detect it but with refrence to what ??


i mean

if the phases is a,b,c and while the operation it become b,a,c it is easy to detect it ............... "while "

but if it come a,b,c and i switch off the electricity and when i switch it on again it come b,a,c ........... so there was no energy in the relay when the phase reversed so how it will detect this .

i don't know much about relayes so forgive me for this question if it is stuiped
 

Re: q : phase failure

Hello,

a phase reversal during operation could hardly be expected, basically the automatic phase reversal is to correct for wiring errors, or on a building site, where the power supplied could be possibly switched-over to a generator . Similar to a three phase motor the phase sequence monitor relay evaluates the direction of rotating field. Two contactors are be switched mutual exclusive dependant on relay signal.

Regards,
Frank
 

Re: q : phase failure

Hi
you can make it
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