Jaxian
Stainless
- Joined
- Feb 24, 2013
- Location
- Santa Cruz
I have a 75hp RPC running a Doosan DNM5700 and Hyundai/Kia SKT250. This a 400 amp service with 200 amp just for the CNC's. They split the service coming in through two 200 amp breakers. So 200 amp for all intents and purposes.
I had a number of problems getting up to speed. First iteration was a 20hp RPC, standard flavor. Just to be able to start the machine and commission it. The machine could sit there turned on but it used an air curtain that had to be up to pressure. So I had an Ingersoll Rand 7.5hp reciprocating compressor. The air pressure would drop every few minutes, the compressor would kick on, then crash the control on the CNC.
Step 2 was ditch the IR compressor and get a Atlas-Copco rotary. I called ready to buy a 10hp and they said No. Rotary compressors must run long enough to get to temperature and burn off the contaminants. They said based on my air needs a 5hp would be better. It would run enough to work. They stressed it HAD to run enough. After the mind numbing noise of a reciprocating compressor I did not want to hear it running all the time. They said it was quiet.
I hooked it in and it was quiet. Like as loud as a microwave oven. It started and ran all the time and I didn't care. But it kept blowing overload relays. The Doosan also did this and freaked out every once in a while. So I invested in a 75hp ADX RPC from American Rotary when it turned out PG&E refused my 3 phase. This RPC has a cabinet full of soda can sized capacitors and is rated for inrush currents up to 6x max rated continuous without the current dipping.
That got me up and making parts and money. But I would still get freakouts every once in a while and I couldn't run the TSC, flood was Ok but the TSC still caused issues. Also the CNC and compressor would get overload relay trips. Finally PG&E came and upped my 200amp service to 400amp. That was ok but the BIG difference and I can't stress this enough was they upgraded my transformer from a 10kVa to a 50kVa. This along with much bigger wires and I never had a voltage drop issue again. You must go out and look at your transformer. If it's a little wimpy one no RPC/VFD or any other magic is going to work.
My voltage was 240v-245v, technically within factory spec..barely, this proved to be the solution to the overload relays tripping. Dealer tech manager said get a transformer and set it to 208v. The machine will be happier. I did and 4 years later I have never had any power issues no matter if I am running both machines flat out with coolant pumps/TSC the works going while the air compressor turns on and runs all the time.
You have to remember it's a system and you should look for the weakest link.
I had a number of problems getting up to speed. First iteration was a 20hp RPC, standard flavor. Just to be able to start the machine and commission it. The machine could sit there turned on but it used an air curtain that had to be up to pressure. So I had an Ingersoll Rand 7.5hp reciprocating compressor. The air pressure would drop every few minutes, the compressor would kick on, then crash the control on the CNC.
Step 2 was ditch the IR compressor and get a Atlas-Copco rotary. I called ready to buy a 10hp and they said No. Rotary compressors must run long enough to get to temperature and burn off the contaminants. They said based on my air needs a 5hp would be better. It would run enough to work. They stressed it HAD to run enough. After the mind numbing noise of a reciprocating compressor I did not want to hear it running all the time. They said it was quiet.
I hooked it in and it was quiet. Like as loud as a microwave oven. It started and ran all the time and I didn't care. But it kept blowing overload relays. The Doosan also did this and freaked out every once in a while. So I invested in a 75hp ADX RPC from American Rotary when it turned out PG&E refused my 3 phase. This RPC has a cabinet full of soda can sized capacitors and is rated for inrush currents up to 6x max rated continuous without the current dipping.
That got me up and making parts and money. But I would still get freakouts every once in a while and I couldn't run the TSC, flood was Ok but the TSC still caused issues. Also the CNC and compressor would get overload relay trips. Finally PG&E came and upped my 200amp service to 400amp. That was ok but the BIG difference and I can't stress this enough was they upgraded my transformer from a 10kVa to a 50kVa. This along with much bigger wires and I never had a voltage drop issue again. You must go out and look at your transformer. If it's a little wimpy one no RPC/VFD or any other magic is going to work.
My voltage was 240v-245v, technically within factory spec..barely, this proved to be the solution to the overload relays tripping. Dealer tech manager said get a transformer and set it to 208v. The machine will be happier. I did and 4 years later I have never had any power issues no matter if I am running both machines flat out with coolant pumps/TSC the works going while the air compressor turns on and runs all the time.
You have to remember it's a system and you should look for the weakest link.
