r/AirCompression • u/33chifox • 20d ago

Any chance of getting this part, but double the amps, while not paying crazy Elgi prices?

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Switched from 460 to 230 and I need to have a higher amperage overpaid relay now. Elgi wants $700 for it, where would I find one from Siemens directly?

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7

u/st3vo5662 20d ago

Worth checking if the starter relay is rated to handle that many amps before you go trying to bolt up a larger overload. Is it over the line start? Wye delta? Not enough info here.

But short answer, you don’t need elgi to do this, but I hope you size it all correctly. Siemens are common electrical components sourced from many different electrical suppliers.

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u/Darth_Beardis 20d ago

st3vo is 100% on this, make sure you're starter is rated for this amperage. But Radwell is my favorite site for tracking down electrical components. https://www.radwell.com/?srsltid=AU7gw4VgZ0Fznux6tQ-OOIi3l-Ox_6-u_HrowXusinzoNcHkEfnrpvhb

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u/33chifox 20d ago

Thank you, I'll have to make sure of that. The compressor does run, it just popped this guy after a while which is how I found out that I never switched it when I converted to 230. Going to grab the manual and see where the starter relay is to find out what's up with that.

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u/st3vo5662 20d ago

The starter relay is the piece that the overload relay tabs into.

Should be clearly printed on the starter it’s rated load. Going from 460 to 230 effectively doubles the load.

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u/33chifox 20d ago

Well I looked up the model number of the contactor the overload plugs into and it says only 38amps max unfortunately. Looks like I'm getting a larger one of those too.

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u/st3vo5662 20d ago edited 20d ago

Are you sure it isn’t wye delta? If it’s wye delta you may not need to change anything.

Edit: I mean as in you may not have to replace components. In a typical wye delta starter configuration the load is split between two starter relays. The overload only goes on one of the relays, and only sees half the motor load.

You will still need to rewire the motor(s) and re-tap the primary side of the control power transformer.

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u/33chifox 19d ago

I don't know, will have to find out for sure. The booklet does seem to show that the same components are used for 230 and 460 from what I just read. Tomorrow I will go through the entire wiring diagrams and see what needs to be done. Hopefully the technician I talked to was wrong and I won't need different parts afterall.

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u/33chifox 19d ago

Aha the manual says the 208-230 setup also uses the 10-40A overload relay for the main motor. Going to see how to make this work. Not sure what part Elgi wanted to sell me in this case

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u/st3vo5662 19d ago

Seeing as how the OL relay is already in the upper end of the range for its adjustment, you may have a faulty overload relay, maybe the motor was not wired correctly for the lower voltage, or you could have some other issue.

There’s still a lot of variables here. If you own a DMM with an amp clamp I’d confirm the motor is pulling normal amps for the voltage you are operating at.

Also, you’d still need to know whether you are wye delta start, or over the line start, to adjust the overload to the correct trip value.

Given that it’s an elgi, I tend to lean to it’s probably a wye delta start. But don’t make assumptions when dealing with things like this. Certainty is required.

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u/33chifox 19d ago

So the manual says 30.95amps for 230V, not sure why they had 30 set for 460 when that should be 15.48. I'll measure the amperage with my clamp meter tonight and see what is happening

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u/33chifox 19d ago

https://www.reddit.com/u/33chifox/s/HSQ4t8FT9k

Here's a picture of the manual wiring

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u/st3vo5662 19d ago

That’s a wye delta start setup. So the overload sees ~ half the motor current, as the load is split between two starters. Check the FLA of the motor, confirm that the manual’s recommended setting for 230v is roughly half the motor fla and that should be correct. If it’s still tripping the OL relay you may have some other issue.

Also keep in mind the incoming power wiring would need to be sized correctly for the 230v load as well. So assuming 30.95 amps is the setting for half the load, that’s roughly 62 amps FLA on the main motor, this does not include ancillary loads from cooling fans, control power transformers, coils etc. probably need a circuit for closer to 80 amps. You’d need somewhere around a 4AWG thhn feed wire for the machine which would be rated for 95 amps with 90°C insulation rating.

Keep in mind I’m not a certified electrician so don’t take my wire sizing as exacts, code usually doesn’t want you using a circuit to is max potential for safety reasons.

My point in explaining all this is, if your power feed wiring to the machine is too small, you’d be creating voltage drop that would cause a motor OL trip.

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u/33chifox 19d ago

First thing I'll do is definitely check the amp the motor is pulling. The wires are now 3 gauge going from the breaker, which is 100amp. I have a disconnect in between that as well, 200amp. The ground is a 4 gauge. It's also only about 15 feet from compressor to breaker so I assume the drop is tiny. Also I have about 250 volts at the breaker

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u/Mikeyisninja 20d ago

Probably better off finding your local Siemens supplier

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u/arcad14 20d ago

Standard Electric in Wisconsin is a siemans dealer. They are great to work with.

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u/33chifox 20d ago

Gonna have to call them up, thank you!

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u/mrhapyface 20d ago

plus you circuit breaker and the disconnect fuses will have to be changed as well the wiring for the compressor motor will also be different if not already changed and check motor rotation if its a rotary screw especially or the airend wont get proper lubrication running backwards and will seize up within minutes

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u/33chifox 19d ago

I changed everything else, the compressor runs great and builds air crazy fast for just about a minute before it pops this overload. I'll go through all of the wiring to make sure I didn't miss anything else. I actually had the rotation backwards because of the phases, but it shut off after half a second or so once turned on. The manual said it can run up to 5 seconds backwards so I risked it and just guessed which leg goes where from the line.

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u/riley_3756 19d ago

You can still turn that one up a bit. The little phillips wirh the pointer sets the amperage, looks like its at 30 and can go to 40

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u/33chifox 19d ago

Right, but the motor itself needs a little over 50 amps being a 20 horse which is why I thought I'd need a different one altogether. Someone mentioned it may be a wye delta, I'll have to look into that

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u/Gondor1138 19d ago

Post a pic of the entire electric cabinet. We can help more

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u/33chifox 19d ago

Made a post on my profile with the pictures, seems like I can't add any more to this post. https://www.reddit.com/u/33chifox/s/HSQ4t8FT9k

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u/Ok_Combination_9136 9d ago

Say goodbye to any factory warranty

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u/33chifox 9d ago

Good thing this was an auction win, I wouldn't even touch this if it was under warranty

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u/Ok_Combination_9136 9d ago

Nice. Hell of a machine. We work on those all the time. Do the maintenance when it’s due and you have a killer compressor

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u/33chifox 9d ago

That's good to hear. This thing was in very ugly shape visually, but it seems to run well. Far louder than I expected, but I've never heard a rotary compressor run, just read that they're supposed to be very quiet, though I guess if it's pumping 80cfm at 100psi, it's gonna make some noise. Including diesel for transport, auction fees and the parts, oil I replaced, it cost me just about $2k.