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#51239 04/26/05 03:14 AM
Joined: Mar 2005
Posts: 1,803
Member
I put this question recently as part of another post, but on re-reading realised it
was confusing, so here it is again, but more accurately. I'm starting 2 s.ph 230v motors, running duplex, a 3.ph alternator. 2 new starters have been fitted, BUT THEY'RE 3 PHASE MODELS, (the only ones I could get locally, this being an agricultural area). Part of the assembly is an overload module, which must be used as the stop switch mech is integral with it. Motors have their own thermal overloads, which I don't think is an issue. I could run each motor, and hence one starter module overload, just through say L1-U , leaving L2-V and L3-W out of circuit, or run all three module overloads in parallel to 'share' the load, or snake through the device in series so:
L1-U , U loop V , L2-L3, W to motor. I have opted for the latter, with no switched Neutral, although that is another option (?) -if I ran L1-U-loop V, L2 to motor, motor return to L3, W to Neutral. I chose 16A models and have set the module O/Ls at 13A. The single phase breakers are 25A each, one per motor.
Have I done this correctly? -I've fired it up and it works- but I can see advantages/disadvantages in all the options.
I start motors in sequence to reduce the initial amps pulled, by the way.
(They're Sneider-Telemecanique LE1D/12 model with LRD16 relay module with a 230v coil.)
Alan


Wood work but can't!
#51240 04/26/05 07:45 PM
Joined: Jul 2001
Posts: 599
J
JBD Offline
Member
The normal method for connecting these overloads is to snake the power wiring from top to bottom so the same current flows through all heaters:
Line -> L1
T1 -> L2
T2 -> L3
T3 -> motor

Or, take T2 to motor and switch the other line with L3 and T3.

If you do not snake the wires the overload relay will trip about 10% fast. This fast trip is rarely a problem except with full loaded motors.


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