Machine fault, I HATE, 1ph motors!

[a1]

Can you post the motor wiring details,make, nameplate data and starter wiring etc (not enough information :slap )My guess is its wired wrongly - has been played with by the owner or someone else

You normally only have 2 sets of run windings for dual voltage 110/230 motors and wire them series or parallel accordingly and both the run windings have to be wired (Start and Finish) correctly

The only other explanation is its not a single phase motor (remember we haven't seen it or the windings) and its a 3 phase motor wired in StenMetx, which if so (long shot) mean the winding resistances are wrong (unbalanced) and could be a motor fault...

I was going to say that. ]

---------- Post Auto-Merged at 09:25 ---------- Previous post was made at 08:04 ----------

Just spoke to my old man (he's older than Deke),

Steps? He said he didn't know.

only other motor he has seen like that (single phase) were GEC ones for grain dryers on farms where again the Run windings were dual voltage only this time they were 230/400

 

[Sidewinder]

Can you post the motor wiring details,make, nameplate data and starter wiring etc (not enough information :slap )My guess is its wired wrongly - has been played with by the owner or someone else

You normally only have 2 sets of run windings for dual voltage 110/230 motors and wire them series or parallel accordingly and both the run windings have to be wired (Start and Finish) correctly

The only other explanation is its not a single phase motor (remember we haven't seen it or the windings) and its a 3 phase motor wired in StenMetx, which if so (long shot) mean the winding resistances are wrong (unbalanced) and could be a motor fault...

---------- Post Auto-Merged at 09:25 ---------- Previous post was made at 08:04 ----------

Just spoke to my old man (he's older than Deke), only other motor he has seen like that (single phase) were GEC ones for grain dryers on farms where again the Run windings were dual voltage only this time they were 230/400

Can't post the motor make or name/rating plate data as there is none!

I have a machine wiring diagram I'll post up later.

I'm guessing wrong wiring, but I thought that I had gone through it and checked/put this right, unless the starter is wired incorrectly, I'll have to have another look, thing is the guy does not want to pay too much, but, I hate being beaten!

Do you have a AT31/33?

 

[apprentice87]

Hi all,

I have found more stuff on single phase motors with THREE windings [instead of the normal two]. Not sure it this will help, but it cannot do any harm!!!

To prevent premature failure of the motor it is essential the motor is connected

correctly first time to the power supply. Correct function and connection of both

Start & Run Capacitors is also vital.

If in doubt follow the simple guide below ...

1. Identify the correct motor Terminals ...

Run - Common (R - C) Lowest resistance

Run - Start (R - S) Highest resistance

Common - Start (C - S) Intermediate resistance

Also R S = C S + R C & C S is normally 3 - 4 times resistance of R C

2 Start Capacitor This is the larger value capacitor in microfarads

(MFD or mFd), typically 100 - 300 mFd.

The Start Capacitor connects between the Run

Terminal and the Start Terminal via the Start Relay.

3 Run Capacitor This is the smaller value capacitor, typically 5 - 30 mFd.

It is connected in Parallel with the Start Capacitor, but

not via the Start Relay, hence this capacitor provides

power to the Start Terminal all the time the motor is

running.

The name Run Capacitor is misleading because it in fact provides power

to the Start Terminal & Start Winding Coil from the power lead to the

Run Terminal.

Important Note On any machine having several smaller Capacitors

added to make a final total they MUST ALWAYS be

group connected in PARALLEL to achieve the desired

value. DO NOT CONNECT CAPACITORS IN SERIES.

4 Start Relay

The high value Start Capacitor would overload the

small Start Winding Coils if left connected permanently,

hence it is normal to disconnect it once the motor has

started. The Start Relay senses the voltage across the

Main Run Winding Coils, which naturally increases

when the motor increases to normal speed. At a preset

level it switches the Start Capacitor off, leaving

only the Run Capacitor in circuit to the Start Terminal.

Single Phase Motor Running Checks

Please read this before Connecting a Single Phase compressor

Final Checks before starting

1 Live & Neutral should connect directly to the Run & Common Terminals.

2 The Run Terminal should connect to the Start Terminal via the Run Capacitor.

3 A second connection to the Start Terminal should be made via the

Start Relay & Start Capacitor.

Once Running

1 Take current reading on Start Capacitor Lead this should show a brief

rise for about 1 - 2 seconds, then drop to zero. Motor tone should

become sweeter.

2 Take current reading on Common Terminal lead this should be equal to

or less than Full Load Current on nameplate.

3 Take current on Run Capacitor lead, this should be about 1/4 - 1/3

Common Lead current.

Cannot hurt, so i thought i would post it!!!!

john..