Fault finding

[wayne]

some motors have the six terminal arrangement which allows your motor to be configured in star or delta while on DOL starting
is the 3 phase motor connected to a DOL starter or star delta starter?

 

[rumrunner]

some motors have the six terminal arrangement which allows your motor to be configured in star or delta while on DOL starting
is the 3 phase motor connected to a DOL starter or star delta starter?

Thats correct wayne. if the motor has the "links" in the delta config ,volt drop caused by the high starting current can cause it to fail to get up to speed

for dol starting it is normal to connect the motor in star

hope this is of some help

 

[wayne]

i also seem to recall star configuration will make it run slower but take more current
its been years since i was taught about voltage /current / kirchoffthree phase .....im rambling like shakey

 

[Spudmiester]

It usually says on the motor rating plate what connection should be, IE 240v star (or star symbol), or 415 delta (or triangle). Best have a look at plate and see what it says.

 

[Shakey]

some motors have the six terminal arrangement which allows your motor to be configured in star or delta while on DOL starting
is the 3 phase motor connected to a DOL starter or star delta starter?

many would have the 6 terminal arrangement, which you need for the starter to be able to re-configure the windings from star delta, most larger motors i have worked on would have 12 terminals, becuase they use two windings per phase

It usually says on the motor rating plate what connection should be, IE 240v star (or star symbol), or 415 delta (or triangle). Best have a look at plate and see what it says.

hi spud, dont see where you get the 240V star 415V delta from

If its a three phase motor its 415 from line to line wether its in star OR delta

Thing that changes is the amount of current being drawn

Cant think of an application where a motor would be started in delta

If it its small enough to get away with a DOL (generally about 3kw or less, then it would need to be in star, if it is big enough to need star delta then it would have to start in star


Plus gents, we are assuming its a star delta contactor (ie a squiirel cage motor)

Could be a three phase resistance starter with a wound rotor induction motor

Could be a synchronous reaction motor, could be an auto syncronous induction motor with with banks of contactors switching resistors out (which is entriely diferent to star/ delta)

or it could be a cage rotor, but using a soft starter with a BPC (by pass contactor) and the BPC has failed

could be running of an invertor

either way, he has implied that this something that has 'happened', which is why you could discount any wiring/confuguration faults

my money is its a automatic star/delta running a squiirel cage, and the change over timer has failed

C'mon fella, give us a clue!!!!!


*Shakey rambles off into the distance*

 

[wayne]

if they dont say, start simple,DOL

 

[Shakey]

if they dont say, start simple,DOL

ok lets go simple

if its a DOL, my money is on burnt contacts on one phase of the contector, give you 3 to 1 on that against a burnt out winding

 

[Spudmiester]

Yes chaps lets start simple, thats what i was getting at, check the plate to see if it is connected as per what it says to make sure the links are right and work from there.

Once encountered a newly wired motor running from a star delta starter and the spark who wired it left the motor links in, and wondered why it kept tripping on start up !

 

[wayne]

im now dying to know the actual fault!!!!!

 

[Shakey]

im now dying to know the actual fault!!!!!

me too Wayne, the chap doesnt seem to have come back

now if he's fixed it and not told us......gggrrrrrrrrrr