3 phase 2 speed motor wiring - need help
I have a motor needs wiring up, was wondering if anyone can confirm that what I am going to do seems correct.
motor in question is a two speed three phase 1.5HP motor, (.375HP at low speed). Made by GE, Model 5K204D1814 for what it's worth. it has 6 wires coming out. some joker took off the plate with the wiring diagram, so I am not 100% certain how to do this up.
My understanding is that if you wire L1,2,3 to the main power, that it will turn at slow speed, and that if you short L1,2,3 together and wire L4,5,6 to the main power that it will turn at high speed. can anyone confirm if this is indeed correct? Don't want to hook it up and burn something out by accident.
sort of helpful, but there are a number of varieties of these, how do you tell which one you have? I imagine it's not rocket science, but I really don't want to let the smoke out of this thing by accident.
Originally Posted by Mark McGrath
Do you have numbers on the wires?
With just a description of it being 2 speed and having six wires, you still don't know if it was 2 sp 2 winding or 2 sp 1 winding. Then if it was 2S1W, there are three different connections depending on the type, Constant HP, Constant Torque or Varible Torque. With numbers on the wires we may be able to help you ring them out with a Multimeter to at least narrow the choices.
And double check the HP ratings. If it's half the hp on the low speed then odds are it's consequent pole I think.
You are more likely right, 2S1W motors tend to be more common and yes if the HP on the nameplate is 1/2 on low speed, then it is a Consequent Pole (Constant Torque) connection. If it's a 4:1 speed relationship, it would be a VT and if the HP is the same in both speeds, i.e. it doesn't say there is a different HP at all, then it is a Constant HP connection.
Originally Posted by jim rozen
...or it still could be 2S2W unfortunately.
at this point I mostly just want it to run at full speed, and hook it up to a VFD. not to much more money and a lot simpler than hooking it up using contactors, etc to change the speed and reverse it.
The O.P. may want to consult this ...
Testing/Identifying Six-wire Two-speed Single-voltage Motors
... "golden oldie" post of mine.
thanks, will check that out.
yours shows for constant HP, mine, I am pretty sure, is not. do you have the info for the other types?
Constant torque, variable torque and constant HP are variations on a theme.
The interconnections are somewhat different, but the concept its quite similar.
The point of the exercise is the motor is symmetrical about an axis, and one can select any of three axes as the reference, and deduce the others.
Of course, these three axes are displaced mechanically by 120 degrees.
so I'm pretty sure my windings look like this:
T1 - T2 = 7.9Ω
T1 - T3 = 7.8Ω
T1 - T4 = 2.1Ω
T1 - T5 = 6.0Ω
T1 - T6 = 6.0Ω
T4 - T5 = 4.0Ω
T4 - T6 = 4.0Ω
T5 - T6 = 4.0Ω
All windings ≈ 2Ω
It looks like when 1,2,3 are hooked up to the power, it runs slow, and when 4,5,6 are hooked up to the power with 1,2,3, shorted together that it runs fast. what happens if you run 4,5,6 hooked up and you don't have the others shorted together? runs fast, but with less power?
what is this kind of motor called? Constant torque? Why would they make these instead of using a constant HP design, if all it would require is to have the windings hooked up slightly differently internally?
Each type has its intended purpose.
Constant torque is perhaps most popular in machinery.
A good source of information on the various options is Square D's catalog of magnetic motor starters.
Sorry to drag up an ancient thread, but I think the info in this thread is relevant to my question.
I have an old (60's) portuguese lathe. I bought it (very) used and the electric speed selection (hi/low) switch was broken. The motor has six wires, and it a two speed variety. From what I'm reading, six wire, 2 speed, 3 phase motors only come in two basic flavors. The first is two seperate windings, one for high speed, one for low. Put power on one set for low speed, switch power over to the other set, disconnecting from the first, and you get high speed. The second is the style in the diagram anchorman posted above.
I'm fairly certain that my motor is the second style, like anchorman's. Here is my rationale, please see if it makes sense before I burn up the motor trying it the wrong way:
1) There is continuity (but I don't remember the resistance) between the two groups of wires, i.e. there are two red/green/yellow groups coming from the motor, and the two reds have continuity. If it were the two seperate windings style, they wouldn't have continuity, correct?
2) Initially, we incorrectly wired the incoming three phases to the set I now know are the "high speed" connections of the motor. We did that without shorting the slow speed set together. The motor ran but was really slow to spin up to speed and had no power (couldn't even turn the chuck in any but the lowest mechanical gear). Once we disconnected that set and connected to the low speed set, the motor snaps up to speed the way it should and has good power. I'm grateful we didn't burn up the motor doing that, but when we did have it connected that way, if it were a "two seperate windings" kind, it should've worked well, not the way it did. So either the high speed winding is half fried, or it must be the "low speed star, high speed delta" type, right?
The lathe speed combinations show that high speed is 2x low speed. I think when I saw the nameplate on the motor, low speed was .8kw and high speed was 1.3kw.
The motor is tucked into the bottom and it's going to be really hard to find a replacement if I mess this one up. On the other hand, I need the high speeds available. Does the evidence point to high speed being 1,2,3 shorted together, 4,5,6 connected to incoming 3ph?
Should I go ahead and give it a try, or is there something else I can test to verify for sure before putting the juice to it?
looks two posts above at the diagram, you should be able to measure the resistance between each wire in a methodical fashion and write down the results in a little table. if the wiring is at all like mine, there should be some base value across a single coil which will be your lowest resistance. the highest resistance you measure will be across four coils, and should be 4x this lowest number.
Originally Posted by JasonPAtkins
if your motor is wired the same as mine, it will not get full power running on the high speed without the other wires shorted together. you need these coils running in parallel (which is what shorting the low speed leads does) in order to get the full power out of the motor.
I don't think you can harm the motor for a short test if it is a single voltage motor, but if it is getting power but not spinning, you may burn it up if you leave it that way for long.
Ok, I measured resistances and think it's similar, but not exactly the same, not even the same ratios necessarily, but similar patterns:
T1-T2, T2-T3, T1-T3, all 13 ohm
T4-T5, T5-T6, T4-T6, all 13 ohm
T1-T4, 8 ohm
T1-T5, 8 ohm
T1-T6, 16 ohm
T2-T4, 8 ohm
T2-T5, 16 ohm
T2-T6, 8 ohm
T3-T4, 16 ohm
T3-T5, 8 ohm
T3-T6, 8 ohm
I'm numbering the wires by their order in the terminal strip, but I think T4 and T6 might be in the wrong order, if I were to relabel them my results would then be:
T1-T4, 16 ohm
T1-T5, 8 ohm
T1-T6, 8 ohm
T2-T4, 8 ohm
T2-T5, 16 ohm
T2-T6, 8 ohm
T3-T4, 8 ohm
T3-T5, 8 ohm
T3-T6, 16 ohm
So that looks mighty similar, except that in my case:
1) The resistance (13 ohm) between the first three (T1-T2, T2-T3, T1-T3) is the same as between the second three (T4-T5, T5-T6, T4-T6), and was not in anchorman's example.
2) In my case, the T1-T4 pair is a higher resistance than the T1-T5 and T1-T6, not lower, like anchorman's. Likewise for T2-T5 and T3-T6.
So, I don't think there's much else left to test. Knowing what I do, should I feel confident I'm not going to ruin the motor by tieing T1-T2-T3 and putting the incoming 3ph on T4-6 for a few seconds?
For archival purposes, it worked like a charm. Tie T1-T2-T3, power into T4-6. Speed in this case is 2x the low speed. Now to find a replacement switch.