Motor trip

Hi,
I am using a 0.18Kw motor to run a belt conveyor.
We are using a thermal motor circuit breaker(GV2-P03:0.25-0.4A,Telemecanique brand)to on the motor.The Mcb trips after 1min of motor running.
On checking the current by a clamp meter it shows 0.2A.
Could someone tell me how to troubleshoot this problem.
We tired setting the trip range to max.Still the motor trips.
The voltage is 3phase 400V.

Regards
Annie

Check you have a balanced load (ie - equal loading on ALL phases), check the supply voltage on the contactor and to the motor terminals (again measure a balanced supply). Are you measuring the load right up until the motor trips? Or, is it intermittent, and is labouring after about a minute?

Check the conveyor is free, and doesn't have any tight or binding sections. Check for mechanical jamming (ie loose bolts etc).

Hope this helps get you started!

Annie said:

Hi,
I am using a 0.18Kw motor to run a belt conveyor.
We are using a thermal motor circuit breaker(GV2-P03:0.25-0.4A,Telemecanique brand)to on the motor.The Mcb trips after 1min of motor running.
On checking the current by a clamp meter it shows 0.2A.
Could someone tell me how to troubleshoot this problem.
We tired setting the trip range to max.Still the motor trips.
The voltage is 3phase 400V.

Regards
Annie

Click to expand...

Annie,

Did you check all three phases? With three amp meters (preferred method), or moving the meter quickly from one phase to the other.


Is there a VFD also controlling this motor?


Are the wire terminals tight on the overload? (sometimes a bad / partial connection will allow the motor to run on all three phases but conduct extra heat to the overloads).


I have never used this device but I see it has some previsions for under voltage dropout. Could this be happening?

Is this an application that has worked ok in the past, or a new install?

Does the conveyor runs constantly, or
in start / stop mode?
I ask this, because the nominal current for
a Motor -> 400V / 0,18kw is 0.6A, so the circuit-
breaker should fit.( 0.4 - 0.63A).
Another thing could be the circuit-breaker
itself.

regards
Rolf

Lessee now
P = I x E x PF x 1.73.
So at .18 KW and 400 volt
3 PH current = 0.26 A (disregarding PF).

Circuit breaker rated .25 to .4 amp. You SHOULD be OK here. It should be set at 125% of full motor current (should find this on nameplate). From your numbers it should be set at about .3 to .32 A.

In my experience these problems run for a while then trip then run for a while are generally NOT electrical but end up being mechanical.

You say a conveyer - what does it convey blocks of lead or blocks of styrofoam ie how much does loading of the conveyer (thus motor) change and how frequent? Does it run constantly or intermittent (ie start stop start stop). If intermittent you may be overheating motor due to too frequent starting current and not enough time for motor to cool itself (probably not the problem as you stated but it surely is not good for the motor and IF your overloads are heater type they need time to cool also SO this could be a cause of tripping) Under what conditions did you take clamp on reading ie loaded or unloaded? YES take ALL 3 phases by the way.

TRY to get current AND line voltage when conveyer unloaded and fully loaded. Look for binding, heating bearings, and other mechanical problems. CHECK gearbox lubricant and for heating and binding. Take several sets of reading one hour apart and do all mechanical checks.

Dan Bentler

hot enclosure?

Don't overlook a hot enclosure falsely tripping overloads.

I once had a remote pumping station that would only trip the overloads in winter time. The enclosure had a protective overhang/roof that shaded the enclosure. Well it turned out that the enclosure was in direct sunlight only in the dead of winter when the sun was lower in the sky. Most of the time the sky was overcast so no tripping. A 6 inch piece of canvas along the south edge of the overhang cured everything.

If the current is approximately equal on all 3 phases, replace the motor ciruit breaker. I have had quite a few of these fail of late, and the Sprechur & Schuh (AB) ones.


Don't even mention the problems with soft starters - cost me a fortune replacing faulty ones all ovber the place.