lkpflk

i have replaced a 415v 3 phase motor at work. The old one had 3 terminals in a line, each with one internal wire connected, and one terminal on other side with 3 internal wires connected. The new one has 6 terminals, each with one internal wire connected. It came with 3 bridging links which i have used. However, when i run motor, it trips on overload after about 20 seconds, and blows a fuse. It also feels warm. Obviously, it is not connected correctly. Would appreciate any help. Thanx.

benji

is the new motor same size/spec. as old one,check plate on motor ,when you connect motor are you connecting it in star or delta (check where you put the links)what size is the motor kw
yours benji

lkpflk

it is a 7.5kw motor, and the same spec as old one. As for star or delta, i don`t know. Just want it to work. Thanx.

sorry, that should read 0.75kw.

jibtech

it sounds like the old motor was connected in "star" configuration

to achieve this the links need to go across the secondary terminals rather than between the two sets

Spudmiester

Read the rating plate and see what it says . Connect links accordingly.

Would draw a picture but dont know how, not much good with computers, but in star, the 3 phases need connecting to U1 V1 W1, and the links want to be accross U2 V2 W2.

In delta it should be the three phases conected to U1 V1 W1 and then linked as follows, U1 toW2, (one link) V1 to U2 (second link) and W1 to V2 (last link)

This is providing it is a standard motor with nothing oddball about it, would be worth checking to see if you have all three phases at the motor, and putting the clamp meter on under load conditions and setting overload accordingly. Have you found out what knackered the old one, because if there is say a phase missing, or a dodgy contactor, then the new motor probably wont last long either.

Let us know how you get on.