Connection of Dol Starter With Multimeter

[formach]

Hye all,

i need some help here about DOL starter im working with right now
View attachment DOL starter.bmp
first i thought that i can just add the multimeter on the circuit. but then my supervisor said i cant just add the multimeter just like that..i have to add some ct coil?
so can anyone here give me some reference about connection or any calculation needs for adding the coil?

 

[telectrix]

just seen your post. can't make out the diagram, it's too small. what do you want the meter to measure? if it's for measuring current, then a coil is required, same as with a clamp meter.

 

[Knobhead]

Same as Tel, I can't read it. If you need to measure current use a clamp meter.

 

[ackbarthestar]

Ditto...
I'm not sure what you are trying to achieve.
1/ Do you want to measure the resistance of a coil used to energize a contactor
2/ Do you want to insert a contactor into the circuit to provide switched control over the circuit

If the former then why bother? DOL contactors are current rated by their switch contacts and for loads over 0.37kW require overload extension bolted onto the assembly. The coils are rated for 230V or 400V

If the latter, then you will need to do some research about contactors and how to wire them up for use.

 

[Knobhead]

Coils are rated at what you specify. 24, 48, 110, 230, 380, 400, 433, 500, 660. You name it, someone makes it.

 

[ackbarthestar]

Yes, agreed. I forgot about ELV control switching

 

[formach]

i hope this image will give u guys a better pic of what i'm going to do..
here is some info about the motor:
rated power: 0.37kW
no.poles: 4
rated voltage: 400
rated current: 1.10
ratio of starting current to rated current:3.2

info about DOL starter:
1.contactor
2.overload relay 1.3-2.1A
3.power meter( still no idea what best i can afford)
4.MCB 6A 1 pole X 3
5. Current transformer 60/5A

1)this motor using wye/delta connection. so i assume the calculation for starting current is 1.1X(3.2/1.73)=2.03A...so is it correct?
2)can my circuit works? based on the info given
3) if there is any recommendation please bring it forward..

Thank you guys for ur time!!

 

[Gazmm]

If it's dol, its either star or delta, at that size is assume star. Also current that low can be measured directly by a multimeter, personally id just clamp it.

 

[Engineer54]

I'm a little confused as to why your asking these questions?? For a start why would you want to monitor such a small motor, What sort of monitoring unit are you connecting the CT's etc too. Whatever unit it is, surely it would come with a wiring diagram??
In other words WHAT are you trying to do, and maybe more importantly, for WHAT reason??

Not sure your stated CT ratio is going to register your motors 1A. lol!!

And still can't see your diagram, very fuzzy to say the least!!

 

[ackbarthestar]

Looks like you want to be able to switch from star to delta, but unfortunately you wont achieve that with a DOL starter.

At present it appears to be set for either star or delta which suggests that in star you will be running at 2/3 speed. If in delta then I suspect the starting current will be higher than you have stated.

 

[formach]

i already done with the dol starter and the motor running perfectly.
but now i want to add the power meter so i can check the current and voltage supply to the motor.
that is what im trying to do.
so if u guys got any idea of power meter suitable for this circuit?
thank for ur time!

 

[Knobhead]

Is this tempory or permanent?

 

[ackbarthestar]

Looks like it a college assignments......

 

[formach]

its a permanent....can i get some advice how to determine the ct spec,its 50,60 or....

 

[SheffSimon]

Not unusual to want to monitor power of a motor, it provides better protection for the connected mechanical load than the motor overload. The mech load may well be damaged if jammed, by the time the motor overload has got around to tripping....essentially the power meter is acting as a shearpin.

You wont need separate CT's for such a small motor, the power monitor would be connected directly to the monitoring relays...have a look at uk.rs-online.com/web/p/monitoring-relays/0465258/ or similar. All this monitor would do is unlatch your starter circuit, not display the actual true power, although pricier ones do.

If you are wanting to display the motor current have a look at www.crompton-instruments.com/datasheets/Analogue_Instruments_REV_04-10.pdf some connected via CT's some directly connected.