Best way to get 480V power to machine with limited options.

HEXx99 · May 14, 2022

The machine is a Sunnen CK-21-E used for Honing. I cannot find any manuals but ill post the tag. I dont believe its multi-voltage which would make this a lot easier for me. It says 480V and its pulling 12 Amps full load.
Location is in a warehouse. Only power nearby is 2ea. 208V panels both being supplied by a transformer. 408/208V ill send the spec for that also. Id like to get the power from the 480V side of the transformer as its very close to the machine but not sure if it will effect the 208 panels . The transformer gets its power from another room . That panel has no room for additional breakers.. The more i think about it the more obstacles Im facing .
If i can make room in that panel could i pull wire to the transformer and through it (not connecting to anything) and run conduit to the the machine?
Actually I would need a disconnect too right? since the panel is in another room? Not in line of sight ?

marconi · May 14, 2022

Hello again from very sunny London.

I cannot advise you on how to wire in the new machine in accordance with the NEC but can offer some help doing early site checks and measurements.

To save time we need to know:

1. The line - line voltage at the input to the transformer - is it 480V or some other figure? Do this for all pairs of lines.

2. The 480V to 120VY transformer is rated at 75kVA. What is the kVA consumed by the current site equipment? We can then work out what spare capacity is available from the 75kVA.

3. What is the kVA requirement of the machine? I am not clear from the specification plate whether the 18.7A refers to the 24DC supply and the 11.9A to the three phase 60Hz supply. For now I will assume the pairing is 24V/18.7A and 460V/11.9A which would mean a total machine kVA of (25 x 20) + (460 x 12 x sqrt3) = 500 + 9600 = 10 kVA

4. Does the machine require a separate 24V dc supply capable of supplying 20A?

5. What is the voltage specification of the machine? You mentioned 480V but the machine's plate says 460V.

6. What are 208V boards Line to Neutral voltages? Are they in specification for the site load?

7. What are the 208V boards phase currents? Are the boards loads roughly balanced?

8. What are the 208V boards neutral currents?

9. Is there a large load connected now to 208V boards which when turned on or during running causes current surges and perhaps voltage dips?

10. Does site lighting ever flicker?

Lucien Nunes · May 15, 2022

Surely the machine full load is 18.7A, of which the largest motor load accounts for 11.9A? This is a pretty common way of speccing machine power where one motor dominates.

HEXx99 · May 15, 2022

marconi said:
Hello again from very sunny London.

I cannot advise you on how to wire in the new machine in accordance with the NEC but can offer some help doing early site checks and measurements.

To save time we need to know:

1. The line - line voltage at the input to the transformer - is it 480V or some other figure? Do this for all pairs of lines.

2. The 480V to 120VY transformer is rated at 75kVA. What is the kVA consumed by the current site equipment? We can then work out what spare capacity is available from the 75kVA.

3. What is the kVA requirement of the machine? I am not clear from the specification plate whether the 18.7A refers to the 24DC supply and the 11.9A to the three phase 60Hz supply. For now I will assume the pairing is 24V/18.7A and 460V/11.9A which would mean a total machine kVA of (25 x 20) + (460 x 12 x sqrt3) = 500 + 9600 = 10 kVA

4. Does the machine require a separate 24V dc supply capable of supplying 20A?

5. What is the voltage specification of the machine? You mentioned 480V but the machine's plate says 460V.

6. What are 208V boards Line to Neutral voltages? Are they in specification for the site load?

7. What are the 208V boards phase currents? Are the boards loads roughly balanced?

8. What are the 208V boards neutral currents?

9. Is there a large load connected now to 208V boards which when turned on or during running causes current surges and perhaps voltage dips?

10. Does site lighting ever flicker?

Ah we meet again! Hope all is welI. I am going back to this site in the morning and will get these answers . Let me see what I can answer now: side note this is the same transformer i changed the taps on last month

1. I will double check but Im almost certain the voltage is 480V exactly going into the transformer.

2. The Rottler CNC is getting power from one of the 208 panels. again .. i will confirm tomorrow but this machine is a honing machine not directly related to the CNC meaning they will not be running at the same time. I can also mention or advise them not to run them both as it may cause one or both machines to not have optimal power. Which would reduce performance. The same holds true for all the other machines that are currently connected to are getting power from either of those panels they're mostly like a drill presses and other specific usage machines that don't get used often they're just necessary for the type of work that they do. They build and modify high-performance automobile parts engine parts etc.I think I will have them turn on the machine and kind of running a little bit so that I can measure the amperage that it's cooling while it's running just so I have that noted noted.

3. I've always gone by the full load amps . which in this case is 18.7A
ahhh.. i found something. Apparently, they usually come with a Square D step up transformer - HV 480▲ LV 240▲ /15 kVa
and ig this one doesnt have.
Will have to determine whats best (cost-wise): buy a step-up transformer or just run directly from the 480v .but im going to say direct would be better. especially since i dont have a full 240v nearby.
alright change of plans Im going to post an update reply.

HEXx99 · May 15, 2022

all right update I'm going to forget the transformer because I don't wanna take any more power from that CNC machine due to issues I already had with it being not enough voltage so I am going to get the 480 power from a panel that is in another room upstairs adjacent to this warehouse I'll just have to run conduit it's going to be about 160 foot run so with 480 V so I guess I could run number 12 but probably safer to run number 10.
I would need a disconnect or safety switch for line of sight I believe that's the code so I'm going to just run the conduit on the ceiling and then drop down to the safety switch and then go back up to the ceiling because there's nowhere else to mount the safety switch and then go over to the machine and from the ceiling to the machine ill use SO cord
But I do see a switch on the machine itself I'm not sure if that's sufficient. these switches are also on compressors .. my dad just usually had us put in disconnect for compressors unless the panel was in line of sight to the machine. and even then only rarely does he not put a disconnect/ safety switch.

Megawatt · Jun 4, 2022

HEXx99 said:
all right update I'm going to forget the transformer because I don't wanna take any more power from that CNC machine due to issues I already had with it being not enough voltage so I am going to get the 480 power from a panel that is in another room upstairs adjacent to this warehouse I'll just have to run conduit it's going to be about 160 foot run so with 480 V so I guess I could run number 12 but probably safer to run number 10.
I would need a disconnect or safety switch for line of sight I believe that's the code so I'm going to just run the conduit on the ceiling and then drop down to the safety switch and then go back up to the ceiling because there's nowhere else to mount the safety switch and then go over to the machine and from the ceiling to the machine ill use SO cord
But I do see a switch on the machine itself I'm not sure if that's sufficient. these switches are also on compressors .. my dad just usually had us put in disconnect for compressors unless the panel was in line of sight to the machine. and even then only rarely does he not put a disconnect/ safety switch.

By the NEC as long as the breaker can be lockable in the open position then a disconnect is not required. Some manufacturing plants require disconnects since they are the AHJ.