200 Volt power supply- Transformer question

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dannyboy1

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I'm involved on a project; incoming power to the customer facility (our machine) is higher than expected (496 VAC). After tapping primary side to max voltage, our expected 220 VAC is coming in at 236. Normally not an issue; but we have some Fanuc LR mate robots who seem to like a lower voltage, and are giving us some regenerative power faults. After changing to an alternate power supply (power tapped from another location for short term use), robots prefer to run closer to 200-208 VAC without issue.

I'm looking to install a second transformer (277 input and <220 output, single phase) in series with our present machine transformer. I have found one through our supplier; and can't afford putting in a higher end constant voltage transformer (looking at 3KVA), and $3000 is out of budget.

Ideally, we would want our voltage to the robots at 200 VAC; and with all calculations; I'm coming up at about 220 VAC for our robot supply. Is there a better way to slice this, getting

Any help greatly appreciated.
 
Welcome. What transformer do you have exactly? to my knowledge, there are no standard 480V - 220V transformers, just 480 - 240 and 480 - 208. I believe the highest tap on the primary side is 504V (+5%). Connecting 496V to that with a 480V - 240V transformer would give 236V on the secondary side like you have.

If you want ~200V on the secondary, you need a 480V - 208V transformer, with the incoming 496V connected to tap #1 (+5%), which would give 203V on the secondary.
 
That is good news.

Presently using a HPS Fortress C1F010LES Transformer (automationdirect.com). I see where you are going; we have other equipment rated at 220; which are tapping this circuit as well. I was hoping to 'clean' or step down from the 240 side; without replacing the main transformer, which could open a can of worms for us on some of the other equipment being under powered.

Is there such thing as a 240-208 general use transformer, without edging into the higher end units or a custom wound unit?

I really appreciate the support/experience.
 
dannyboy1 said:
That is good news.

Presently using a HPS Fortress C1F010LES Transformer. I see where you are going; we have other equipment rated at 220; which are tapping this circuit as well. I was hoping to 'clean' or step down from the 240 side; without replacing the main transformer, which could open a can of worms for us on some of the other equipment being under powered.

Is there such thing as a 240-208 general use transformer, without edging into the higher end units or a custom wound unit?

I really appreciate the support/experience.
Click to expand...


Not sure if you need 1 or 3 phase, delta or wye configured, what kva rating, etc. but they do make off the shelf 240 to 208 xfmrs:

http://www.larsonelectronics.com/p-...ngle-phase-to-208-vac-single-phase-11kva.aspx

or what's called a buck/boost transformer.
 
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