jraef: Thanks again for another great reply. I have been in the industrial UPS market for so long that I take for granted that everyone knows the distinction between a true industrial UPS and a commercial UPS. The main difference is that an industrial UPS will ALWAYS have an isolation...
Thanks for the replies.
DPC: Thanks you for clarifying the current limiting breaker. The reason for the this is that our company does not have a minimum guideline at this time and rely on the customers requiremnts. We completely understand that all of our customers have more stringent guidelines...
I am trying to come up with a definitive answer to what PPE is required for my technicians to use when taking voltage measurements on a 480VAC input UPS less than 100KVA with a nominal 120VDC buss. Looking at the NFPA 70E tables it states that that panelboards or other electrical equipment rated...
Scotty: I have no experience with the Protect 8. Only with the older industrial systems such as the transobloc and a little knowledge on the protect 3.
As a note, I haven't managed to get someone back to the site to look into the problem further. I do have someone going within the next two weeks...
"You'll get a current reading when the CT is moving. I'd suggest a scope to see how much ripple voltage there really is. "
The amp clamp did not have to be moving to pick up the field. If it was stationary next to the battery the reading was still very high.
They did attach a scope (Fluke 190)...
A technician of mine was performing battery maintenance on a UPS battery containing 2 strings of VRLA batteries. Each string had 40 jars, 240 Cells and were being float charged at approximately 530VDC. The battery is connected to a commercial type UPS (Powerware 9355) which has no isolation...
davidbeach: "The output is in phase with the phase-phase voltage input, not with the phase-neutral voltage. ".
I understand the phase neutral relationship as I have previously mentioned. Everyone has stated that the 208 will be in phase. If this is the case if I attached a scope to the input...
I have attached a sketch I made today. I am at another site today. The phase difference is between the A phase input to the UPS and the A phase output of the UPS after the output transformer. These terminals go to the bypass switch contacts. A Fluke was connected between these terminals on AC...
Sorry! One more detail. The UPS is 208 single phase in 208 single phase out. No delta wye transformer in the UPS.
UPS Service Manager http://www.nolanpower.com
Thanks for the replies.
As usual, I have read my thread again and found that I missed out an important detail!!!
The UPS is 208 in to 208 out. They have just chosen to use only one leg of the 120VAC out (A phase to neutral)as their load supply. I understand that the output 120VAC to neutral will...
Hopefully someone can help me understand the following:
We have a UPS that was installed in the 80's. The input is from the A and B phase of a 3 phase 480/208 delta/star transformer at 208VAC. The UPS has an internal output isolation transformer on it. The plant take the A phase to neutral...
Just be aware that the VRLA charger will be designed to charge 12 cells (nominal 24V with a float charge voltage of approximately 27.2VDC). A Ni-cad battery will more than likely have 20 cells which will need to be float charged at 28.4 - 29VDC. It may also need to be able to boost charge the...
Capacity test: Discharging a battery according to the battery manufacturer's data sheet at a specific current for a specific duration.
Acceptance test: As above but for a brand new installation
Modified performance test: A test, in the “as found” condition, of battery capacity and the ability of...
Scotty
The Grouser is one of the best earth fault testers I have used. Old school in the leather case!I can't find them in the USA but I think they are still available in the UK. I would love to get my hands on one in the USA as I have had many instances where it would come in handy!
UPS...
Is the insulation resistance monitoring device made by Bender? If so this unit causes some very unusual readings when you go between ground and the positive or negative bus. This is due to the way that it monitors faults. Try and disconnect the monitor from the system and then read your...
We have a PWM UPS that replaced an old Ferro UPS. The site decided to re-use the bypass tarnsformer from the original UPS. This transformer is a ferroresonant constant voltage transformer.
When commissioning the new UPS it was found that the UPS seems to work as designed. The problem only arises...
IRstuff: Yes he should be using a 10x probe as that is the equipment that we gave him! Also- manufacturer very unhelpful as usual.
Gunnar: I was referring to L-GND as the output of this UPS should have the neutral grounded.
UPS Service Manager http://www.nolanpower.com
VE1BLL
You have just confirmed that I am definately going senile! I just checked my threads and I did already post this problem last year. Everything blends into a blurr after a week or so!!!!!!
UPS Service Manager http://www.nolanpower.com
I have a colleague who is working on a three phase UPS (MGE Comet). He attached his scope to the output and he is getting 480VAC phase to phase and a perfect sine wave which is as expected. He is reporting that when he goes from phase to neutral he gets a 277V saw-tooth. I do not have any...
Consider a single UPS system:
In nearly all UPS systems there will be an internal transformer on the output of the inverter. The UPS monitors the synchronisation after this transformer. Therefore the output of this transformer is synchronised to the bypass supply at this point. Therefore no...
