# Ingersol Rand Euro compressor start up fault



## Lew_boi (Oct 22, 2015)

First post and I'm asking for help already ! 
Picked up an Ingersol Rand, 150ltr 240v euro compressor abit ago. Tried it and everything seemed dandy, built air up, tripped in and out fine etc... Went to use it for the 1st time properly and........ Pop, spark + smoke.

Took the lid off the connection box and it's full of water : ( Seems it lived outside in all weathers in a past life. Dried it all out tried it again, seems to spark from the motor relay and the starter capacitor smokes and smells fried. 

Problem is I can't find any genuine parts for it and the spec printed on the capacitor is half worn off. Anyone know what spec cap I should replace it with ? I'm no electrician so learning as I go with this......

This was the initial fault. Since then I've replaced the starter cap with a 50uf as advised (does this sound about right ?) hooked it up and it started up as it should but as it reached something like running speed it again blew the starter capacitor to bits. 
Anyone got any ideas as to what the problem could be or where to look next ?
Arm in the contactor moves freely and isn't corroded shut.


Details of compressor are : 
Ingersoll Rand Euro compressor 
150ltr
Model no. EN4D30
CPN. 92514207

Details of the top of the motor box :
Type. 1M90L2D
No. 5280/2
1P. 44
kW. 2.2
240v
13.8A
50 Hz
3 HP

Thanks in advance for any help,
Lew


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## Osviur (Sep 7, 2015)

*Dual capacitor motor*

Hello

I have followed your problem and seen it in other forums. It is really difficult to obtain infopmation from IR, in its page your compressor model does not exist neither the motor type.

This motor, single phase, 240 v, 50 Hz, as used in UK, requires not one capacitor, but two, because one (the bigger one) is used to start the motor and other to mantain running it. It is called a start run capacitor motor

In a three phase motor (simplified) there are 3 main windings in a circular form which are energized in a soft sequence, creating a rotating magnetic field. This field induces currents in the conductors of the rotor (induction motor-squirrel cage rotor) dragging it to reach the rotating field. This can not be done because there must be a difference in the two speeds to mantain the induction. Thats why the speed of these motors is always a litttle less than the rotating field speed (synchronous speed) to say 2850 RPM (for 50 Hz), 3540 RPM (for 60 Hz) in two poles motors, 1450 RPM, 1720RPM for four poles motors etc. Being the syc speed 3000 RPM, 3600 RPM, 1500 RPM and 1800 RPM respectv.

In a single phase motor there are two main windings opposite one from the other, in this condition it is not possible to stablish a rotating field but a "jumping" magnetic field, this field will only make vibrate the rotor, unable to create a torsional pair to turn it and try to reach the fluctuating magnetic field. In this condition a induction motor actuates as an electric transformer with its secundary winding (the rotor) in short circuit, taking a very high current (5 to 7 times the normal).

To overcome this condition there is an auxiliary winding displaced 90 degrees fed throug a capacitor to retard the current in this aux winding. In this way, there are two fields that create a rotating field enoug to start turning the rotor and when it reaches about an 80% of the nominal speed, the auxiliary winding (start w.) is disconnected by means of a centrifugal switch (located in the rear of the motor shaft) or a relay. The most common start relay is one that has a coil with a very thick wire and a few turns that is 
connected in series with respect to the main winding. At the first moment, when power is connected a very high current is taken in the main windings so the magnetic field developed in the start relay core, atracts, against a spring, the armature, pivoting it and closing the contacts fixed to the armature ( an iron plate). These contacts close the auxiliary or start winding circuit and the rotor starts turning. As the rotor speed increases, the current taken by the main (or work) winding decreases up to the point that there is not enough atraction in the relay's armature and it is released, opening the contacts, desactivating the start winding. The cetrifugal system does the same function, but mechanicaly.

In this case this single phase motor has two capacitors connected in parallel, but one, the start cap, is connected in series with the start relay contacts. The other one remains connected all the time in series with the start winding, helping to reinforce the starting torque and maintaining a little displaced magnetically field, increasing the working torque.

The starting cap in a 3 HP (2.2 kW) 50 hZ 240 V is aprox. 60 Uf 330 VAC, the other one has less capacity. I could not find a certain value and is very important as explained. Anyway I do not understand why a starting capacitor blows out during a failed start.

In the pictures seen in other forum it is possible to see the relay contacts, very near, too near, pressed by an adjusting screw that forces the contacts to be so close. Try to give at least 1/8" (3 mm) of distance for a better operation.

I would recommend you, to remove the belt during the attempts to start the motor, up to find the final solution. 

Regards.


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