fan tripping breaker

[wrinklyazza]

went to job late today 2 new fans fitted with speed controllers working fine until you turn them up to max speed and it trips out. Then the whole site had gone down it hadnt just tripped the mcb but the mccc feeding the db. This happened twice was doing some investigating when the site agent said we had to leave site. got to go back tommorrow and carry on

 

[telectrix]

start up current??? or are the fans too big for the OCPDs?? need more info. e.g. what does manufacturer specify ??

 

[wrinklyazza]

manufacter specifies dedicated supply which it is on they only pull 3.9 amps on start up and 3.2 amps when there running the controller is rated at 5 amps

 

[telectrix]

so, cable size? OCPD rating? actual current measured with clamp meter?

 

[wrinklyazza]

so, cable size? OCPD rating? actual current measured with clamp meter?

Cable size is 1.5mm. The OCPD is a 6 amp type C like manufactor specifies this isn't trippiong the 125 amp is suppling the DB. The current ratings I gave u were taken with a clamp meter

 

[telectrix]

so, what is tripping. a 125A MCCB?

 

[wrinklyazza]

Yes the 125 amp is. The fans work ok until u turn them on to full and it just trips

 

[telectrix]

check the other loads on it. could be on it's way out.

 

[Knobhead]

Turn off some of the loads fed from the 125 MCCB and try the fans again.

 

[Marvo]

Could be just coincidence, I would be probably be looking elsewhere for the tripping problem if they're 3A fans on a 125A MCB. If it's not overloaded check the terminations aren't getting hot and check the main neutral terminations.

 

[Knobhead]

I think we’re only being told a part of the story Marvo. As per usual.