There is probably a start capacitor, a start coil and a centrifugal switch to switch the start circuit off when the motor is up to speed. Two possible problems that can occur with motors left in storage for a time is the capacitor degrading for some reason but possibly more likely is the centrifugal switch jamming. This is a mechanical operation and dust and grease can jam it up. It is often possible to hear a click as the switch makes contact after power is switched off when the motor is spinning down. Since you can get the motor to run I suggest running it then turning off the power and listening for this click as the motor slows. If you hear nothing then the next step is to open up the motor casing (with power disconnected) and seeing if the switch is jamming and can be cleaned and put back into use.

Martin

Edited By Martin Connelly on 08/01/2016 19:09:55

The clue here is , the motor runs in whatever direction you spin the shaft ! If the shaft spins really freely it should run without having to spin it by hand and only a second or two of buzzing, but the direction it runs will be pot luck, Due to the position the rotor stopped at when last came to rest . I have a motor 1/4 hp 1428 rpm does the same thing, set it going which ever way you want by giving a spin by hand then turn the power on. Its never had capacitor fitted, there is a centrifugal switch inside and the way this is configured with the start windings makes it a run either way motor. It makes sense that ones meant to spin by hand. how else are you going to get it going in direction you want ! Yes you can use a nvr switch and i dont think there is any thing wrong with your motor, the motor i have is at least 90 years old .

b.    that is much younger than the one i have !

Edited By bodge on 08/01/2016 21:14:01

very slight hum.Graham

Sounds like all is well then. Nice motor, run either way motors are maybe a bit rare, yours is the only other one i have heard of.

b.   best to spin motor shaft first then quickly switch power on, gives the start winding a bit easier time of it

Edited By bodge on 08/01/2016 21:43:20

Looking at your photo of the terminal box, Z2 appears to be not connected. This is the end of the start winding and should have a start capacitor connected between Z2 and neutral.

Agree with Andrew and if it goes the wrong direction change those 2 wires around.

Try a 6uf 400volt motor rated type to start with, should be enough to kick it away.

Emgee

Edited By Emgee on 08/01/2016 22:26:45

Pretty sure that rating plate indicates a 10uF 400v capacitor

Pretty sure that rating plate indicates a 10uF 400v capacitor

Bruce

i think it reads that way too, it maybe the capacitor is internal, i have a 1/2hp compton/parkinson with internal start cap. But op says run either way, so one still has to give a spin to get required direction

b.

probably why he thinking of using it t/c grinder. the motor i have, the contacts & c/f switch are configured different to the other motors i have and no amount of capacitors are going to make any difference to which way it runs, its either pot luck or spin it the way you want it go

b.

Edited By bodge on 09/01/2016 00:02:45

Edited By bodge on 09/01/2016 00:31:33

I agree with the comments that the start capacitor is missing, As the motor information plate gives the rating of the capacitor I think you should get the right one (Unless you have one in stock between 6 an d 15 uF It must be at least 400 volts AC rating.) If the motor runs in the wrong directon swap over the Z1 and Z2 wires. This is one source on ebay   This wire ended one would be better as you would not need to mount it in a box.

Les.

Edited By Les Jones 1 on 09/01/2016 09:01:19

Here is the circuit. W1 and W2 are the windings. One end of each is commoned, the capacitor is connected between the others, and the changeover switch applies live to one end or other of the cap. To ensure the motor runs in opposite directions both windings need to have the same sense, I.e. Common the wires of the same colour. You need a separate zero volts on off switch in circuit too.

I agree with Emgee's comments that this simple reversing method is only suitable for motors with IDENTICAL windings and no centrifugal switch. If the OP needs the motor to be reversible we can give him a diagram of how to do it.

Les.

Hi All, The vast majority of single phase motors will run in either direction. They need a kick in the right direction to start them. there are various ways, both electrical and mechanical, to do this, but by far the most common is the starting capacitor. The capacitor should be in series with the start winding and centrifugal switch (if fitted) to reverse the direction of the motor you reverse the polarity of the start winding (swap the ends of the start winding over) reversing the capacitor connections makes no difference to direction of motor running. Always check that the working voltage( Sometimes written as Wkge) of the capacitor is higher than the supply voltage, 400v for single phase, and 600v or above for three phase. On some centifugal switch type motors there is a capacitor connected on the starting winding side of the switch, which can be marked intermittently rated or int rat. This type, though uncommon today, is designed to be switched out of the circuit by the centrifugal switch after starting, and is not suitable for use as a starting capacitor in a motor without a cent switch, as these stay "live" all the time. note also that this is not the same as intermittent rating or continous rating on the motor spec plate, this actually refers to the motors duty cycle.

Phil

If the rotation of the motor would be wrong, could He buy a reverse capacitor to change direction, or must it be plugged in the other side of the room to get the other phase?