Hi, i have an old milling machine to wire with an old 5hp single phase motor as the power unit. it came with an old MEM starter unit. Its a series parallel low starting current motor starter. I would like to fit a new starter unit but i am unsure what to fit as everyone tells me a DOL sarter unit will do it but im not sure as i have very limited experence with motors. The connections on the motor are marked A1, A2, A3, A4, Z1 and Z2 if this is any help. thanx for your help
series parallel motor starter.
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I`m afraid I can`t help you much there. Welcome to the forum. I would expect Sidewinder or Canoeboy will have the information you require.
the series parralell set up (I think) was used a lot in situations where there was high volt drop. The motor windings (start and run single phase) are arranged in series for start up and then revert to paralell when running at full speed. My opinion is a DOL would do but unsure of the motor designations - I take it theres a capacitor across the start winding?
As KME says our resident control experts will be along soon hopefully with better advice.
As KME says our resident control experts will be along soon hopefully with better advice.
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A modern variable speed drive with soft start?
DOL a lot cheaper... I think he wants to know what the motor terminal markings represent
OOo I think those things have resistors in series PJ , don't go diving in there with a DOL until you have all the facts . 5HP will have a fairly high start current too, on DOL. See what the Dynamic Duo say.
Just quickly whilst finishing dinner, off back to work in a mo.
Welcome to the forum, pjh555.
Be careful as, just like building wiring, when you upgrade the machine wiring you must upgrade it to comply with the latest specs, however, in this case it is statute law driven.
What make is the machine & motor, is there nothing inside the lid of the motor TB?
What is the existing motor plate saying, is there a start cap, a run cap is it perm cap?
What is the part numbers etc on the original MEM starter?
As Deke says 5Hp is quite a large motor for DOL especially on 1ph!
See what Dinghy Dave says in a bit, I'll check back after I finish later.
Welcome to the forum, pjh555.
Be careful as, just like building wiring, when you upgrade the machine wiring you must upgrade it to comply with the latest specs, however, in this case it is statute law driven.
What make is the machine & motor, is there nothing inside the lid of the motor TB?
What is the existing motor plate saying, is there a start cap, a run cap is it perm cap?
What is the part numbers etc on the original MEM starter?
As Deke says 5Hp is quite a large motor for DOL especially on 1ph!
See what Dinghy Dave says in a bit, I'll check back after I finish later.
View attachment 2519View attachment 2520View attachment 2521, sorry for the delay ive had trouble uploading the pics. the motor is a capacitor start capacitor run motor. im not sure on the model number of the starter, but its an old starter with a handle where you had to pull the handle down to start the motor and when its up to full speed you then have to push the handle up to run the motor.
your attachment doesnt seem to work. it sounds like there are 2 windings a1 - a2 and a3 - a4 and the capacitor could be z1 - z2? if this is the case then you need to find which winding is the start and which is the run. Then a dol starter could be arranged to start the motor with the capacitor wired across the start winding?
however I stongly advise you to post more info so sides and boaty can check it out.
If you wnat to add pics use 'advanced reply' and choose the option of managing attachments and you should be able to put the pics in your reply
HTH
James
however I stongly advise you to post more info so sides and boaty can check it out.
If you wnat to add pics use 'advanced reply' and choose the option of managing attachments and you should be able to put the pics in your reply
HTH
James
]View attachment 2595View attachment 2596View attachment 2597View attachment 2598 sorry for the delay again, my friend was away and i couldn't get access to the machine. The machine was bought second hand on ebay and was disconnected when my mate collected it, so i don't know which wire went where. There are 5 wires and one earth wire going to the motor, the capacitors are wired in parallel and are the value of 500-600 mF and 150 Vrms, thay are connected to Z2 and then lead onto the motor. thanx for your help, pjh
phj,
Sorry about this now gonna ask for more pics!!!
Pic 1 MEM isolator above the starter I'm guessing?
Any pics of the starter cover or any data plates on that?
Can you get a close up of the interior of the motor terminal box please?
Sorry about this now gonna ask for more pics!!!
Pic 1 MEM isolator above the starter I'm guessing?
Any pics of the starter cover or any data plates on that?
Can you get a close up of the interior of the motor terminal box please?
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Pic 1 is the starter. I wired one of those as an apprentice.
Push the handle down, it puts the rotor and stator in series for start up, but won't lock in that position, you have to hold it.
Once the motor reaches full speed let go of the handle, then pull it up. That puts the windings in parallel run mode and the solenoid holds it there.
EM stop or power failure and the starter drops out of run mode back to it's central OFF position. (note that wouldn't meet current safety requirements, but that was how it was done then)
I also wired a 3 phase star delta version but that was switched with contactors.
But it was all a long time ago.
There are probably 2 stator windings, and the capacitor gives the phase shift to one of the windings to determine the motor's direction.
I would guess in that case that A1 and A2 is one stator winding, A2, A3 is the other stator, and Z1 Z2 is the rotor. Can you try some measurements with an ohm meter to see if that is true?
Can you find a model or part number on that starter, perhaps a google search might reveal the connections, otherwise it's going to take a lot of working out to determine what connects to what and probably beyond a forum looking at pictures.
The box above the starter, just out of the top of pic 1 will be the isolator. So you have the input supply connections to the starter identified.
So if you fancy trying some live tests (usual live working precautions) apply power to the input, put the starter to RUN mode, and determine where the supply comes out of. As both rotor and stator will be in parallel in run mode, you should find L and N each coming out from 2 places. One will be the rotor connections, and the other the stator connections. You can also of course determine that with dead tests with an ohm meter which is probably much safer.
Usual disclaimer, if you re not 100% confident, don't try that.
Once you have identified the two output pairs, connect it up and give it a try. One pair will go directly to the rotor, the other pair will go directly to one stator, and via the capacitors to the other stator.
Push the handle down, it puts the rotor and stator in series for start up, but won't lock in that position, you have to hold it.
Once the motor reaches full speed let go of the handle, then pull it up. That puts the windings in parallel run mode and the solenoid holds it there.
EM stop or power failure and the starter drops out of run mode back to it's central OFF position. (note that wouldn't meet current safety requirements, but that was how it was done then)
I also wired a 3 phase star delta version but that was switched with contactors.
But it was all a long time ago.
There are probably 2 stator windings, and the capacitor gives the phase shift to one of the windings to determine the motor's direction.
I would guess in that case that A1 and A2 is one stator winding, A2, A3 is the other stator, and Z1 Z2 is the rotor. Can you try some measurements with an ohm meter to see if that is true?
Can you find a model or part number on that starter, perhaps a google search might reveal the connections, otherwise it's going to take a lot of working out to determine what connects to what and probably beyond a forum looking at pictures.
The box above the starter, just out of the top of pic 1 will be the isolator. So you have the input supply connections to the starter identified.
So if you fancy trying some live tests (usual live working precautions) apply power to the input, put the starter to RUN mode, and determine where the supply comes out of. As both rotor and stator will be in parallel in run mode, you should find L and N each coming out from 2 places. One will be the rotor connections, and the other the stator connections. You can also of course determine that with dead tests with an ohm meter which is probably much safer.
Usual disclaimer, if you re not 100% confident, don't try that.
Once you have identified the two output pairs, connect it up and give it a try. One pair will go directly to the rotor, the other pair will go directly to one stator, and via the capacitors to the other stator.
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Yes you may well be right, so I hope I've not caused confusion.
The problem with this problem is lack of information.
I'll go with asking for a better rating plate pic too! 
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Seems like you have all the information there already, including the wiring diagram.
A1, A2, A3 and A4 are the motor windings and I would say the motor terminals Z1 and Z2 connect to the capacitors.
Confirm those with some ohm meter tests, then connect it as per the diagram you have, and Bob's your fathers brother.
Locked to prevent being resurrected (again)
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