3 phase 230/460 air compressor install questions
Hello, This is my first post so here, so go easy on me. I did residential electrical for several years.. lots of rewires and service work. But now I'm doing high school maintenance, and I have ran into my first 3 phase situation and I really need some help. I should post photos but I dont hve my camera so I'll just explain the install situation.
We have a s&b type 707 230/460 air compressor that I have halfway installed. The wiring is holding me up. It is 3 phase service with a big mag starter in the panel. There is a small diagram on the compressor that shows (numbers may not be exact, I can go check) 6and9 go to big wire 1. 5and8 go to big wire 2. 4and7 to big wire 3. something like that. the old compressor was wired that way also,, and the wires came twisted when I opened the new compressor panel. so that part was easy to figure out.
the part that has me confused is in the same panel on the compressor, there are wires 1, 2, and 3. I would think these wires are all bundled together like on the old compressor,, even though the old one was 230 volt only. then there is a pressure gauge relay (I think its a relay) on the compressor with 2 lines, and 2 motor screw terminals. well, there is only one motor, so is it like the old compressor where I only use 1 line and 1 motor side of this box? well, thats what I tried.... but i cant get the thing to start. there are 2 12 thhn wires coming from the mag starter... one is mounted on top of the 1 terminal. and the second is wired on boxes sort of on each end of the mag starter.. this second one is hot when I flip the switch,, and the first one is not.
can anyone tell me how to wire this thing? I cant get the mag starter and pressure relay thinggy on the compressor to do their thing. I can get photos later i think.... but I do beleive there will be people here who can do this hopefully without photos.
I really need to get this thing up and running this week thanks for any help.
1. do you have a 3 phase supply? if so,what voltage?
2. Picture or nameplate info is helpful?
Did an installation manual come with it?
Can you post the web site of the manufacturer and give the specific model number. (707? 707-?) Or a link to the installation manual?
If it did not come with any documentation, I would say I can't install it without instructions!
Yes thanks for asking. it is a saylor beall 707. here is the link... there is no wiring diagram in the manual thats why i'm so confused.... maybe with the diagram I would figure it out.
it just says to hire an electrician.... thing is..... even electricians need manuals for 3 phase stuff from time to time.
yes, it is a 3 phase supply going to a pretty good size mag starter in the same panel. I will go get the nameplate info shortly. thank you :)
Well I would say to the "boss" that it came with no wiring instructions and you want to "be sure" you are connecting everything correctly...
Then I would contact the manufacturer and ask for wiring instructions.
If I were installing this, I am good at this stuff, but for an expensive piece of equipment, I would want to be *sure* I was connecting everything correctly. Thus I would prefer to read through an installation manual first. (Which had specific wiring directions...)
And some electric motor connections can be quite complex - 3-phase or even just single phase!
This might take a while.......lol.
There are two facets to connecting this compressor; power and control.
First, control. It sounds like the incoming power is 208 or 240 3ø, is this correct? If so, make sure the coil on the mag starter is 208, 230 or 240 volts. If the incoming power is 480 volts, the coil needs to be 460 or 480.
The box that has 4 terminals in it is the pressure switch. Connect the wire from the L1 terminal of the starter to one of the outside screws on the pressure switch. Connect the two center screws together. Connect the other wire from the starter to the other outside screw. Make sure the overloads are reset in the starter.
Disconnect the 3 wires from the bottom of the starter (these go to the motor, we'll reconnect them after we get the controls to work). Apply power. The starter should engage, but the motor won't start.
Now for power wiring. How many wires are there in the motor? It sounds like 9; are they labelled T1 through T9? If so, you'll need an ohmmeter to determine if the motor is wound wye or delta.
Put one of the meter leads on T2. Test for continuity at every other motor lead. If there is continuity between T2 and T5, but not T2 and T7, the motor is wound wye. The 208/230 volt connection is as follows;
Incoming line 1 = T1 and T7.
Incoming line 2 = T2 and T8.
Incoming line 3 = T3 and T9.
T4, T5 and T6 splice together.
If there is continuity between T2, T5 and T7, the motor is wound delta. The 208/230 volt connection is as follows;
Incoming line 1 = T1, T6 and T7.
Incoming line 2 = T2, T4 and T8.
Incoming line 3 = T3, T5 and T9.
If you need more help, feel free to write back.
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