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Need Help! Uninterruptible Power Supply (UPS)

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kengloong

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power cube 750g2

MODERATOR ACTION: all your 23 posts are only because you want to repair an UPS don't you think you have asked enough??

Anyone can give me some idea on what's possibility Part Fail/ Faulty if the UPS doesn't give any output voltage during it's run on battery?

I wonder why I already replaced 4pcs Power MOSFET and the Voltage regulator IC but the system still fail.

For your information, during the UPS run on battery, it's indicated the UPS failed and doesn't give output voltage. So, when I switched on the UPS again (Switched on the Incoming Supply). The relay doesn't working to cut off the supply from a battery after the supply take over by commericial AC supply.

The Power MOSFET original part number is STP60NF06, but unfortunately I can't get it, so I replaced it using STP60N06. Same to Voltage Regulator IC, I replaced LM317 instead of original part number is LM317T. Is it will affected the system?

Hope someone can give me an idea how to solve my problem.

Thanks!
 

pit

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hip4080a

Hello!

Manufacturer and model no of UPS? (I hope it's not APC)

CU

Added after 12 minutes:

pit said:
Manufacturer and model no of UPS? (I hope it's not APC)
No need, I searched for your posting a few weeks ago.

CU
 

kengloong

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apc ups mosfet

The Manufacturer is RIGHT POWER UPS and the model is Power CUBE 750G2.

Hope you can help.

Thanks!
 

pit

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right power ups power cube 750g2 guide

kengloong said:
The Manufacturer is RIGHT POWER UPS and the model is Power CUBE 750G2.
Never heard of... I hope it's not an OEM product of APC. Does the UPS still have a huge and heavy output transformer?

So it seems to be a standby (offline) UPS? i. e. mains is normally on throughput, only when primary mains fails the DC/AC inverter is started and a relay switches over to DC-/AC output?

Have the four transistors been defective, or why did you exchange them?

How old is the battery? If the battery is older than 5 years it may no longer be capable of supplying the inrush current when the DC/AC inverter starts, so voltage will break down and nothing works.

Have you tried with good (new) well charged batteries?

I have already seen UPS fail with blown up power stage due to low battery voltage or short breakdowns during switch-over. Very poor design, no undervoltage protection, no failsafe H-bridge.


CU
 

kengloong

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battery for ups singapore

kengloong said:
I wonder why I already replaced 4pcs Power MOSFET and the Voltage regulator IC but the system still fail.

For your information, during the UPS run on battery, it's indicated the UPS failed and doesn't give output voltage. So, when I switched on the UPS again (Switched on the Incoming Supply). The relay doesn't working to cut off the supply from a battery after the supply take over by commericial AC supply.

The Power MOSFET original part number is STP60NF06, but unfortunately I can't get it, so I replaced it using STP60N06. Same to Voltage Regulator IC, I replaced LM317 instead of original part number is LM317T. Is it will affected the system?
The Power MOSFET and the IC I already replaced accoring to the above mentioned part nember cause of the transistor and the IC was defected (burn up).

The transformer still produced +- 16.56VAC.

For your info, the battery (new purchase) should be working if I started up my UPS, right?

Is the part number that I replaced is compatible with the original one?
 

pit

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crt monitor need to ups

kengloong said:
kengloong said:
For your info, the battery (new purchase) should be working if I started up my UPS, right?
Not neccessarily, if the battery is not charged or at least not charged enough the UPS won't start.
Is the battery being charged when the UPS is in standby mode? Charging of lead-acid batteries is done with up to 2.4 V per cell during charging, this will be reduced to 2.3 V per cell when battery is full.
WARNING: depending on the UPS the battery may be not isolated from mains, so use a security transformer when measuring life circuits!

Is the part number that I replaced is compatible with the original one?
They are not identical, the STP60NF06 seems so be faster during turn-on than the STP60N60. But you may check the MOSFET driving stage. I assume these four transistors are arranged in a H-bridge?

CU
 

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uninterruptible power supply (ups) circuit

When I measured the battery output, the output voltage is 11.99VDC. When I switched on the UPS, the output of the battery is 12.16VDC. So, is it the circuit charging the battery?

Can you explained more about the H-bridge circuit? How the configuration to design this circuit?
 

pit

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site:www.edaboard.com mosfet+burn

kengloong said:
When I measured the battery output, the output voltage is 11.99VDC. When I switched on the UPS, the output of the battery is 12.16VDC. So, is it the circuit charging the battery?
Possibly yes, you may measure the current into the battery.

Can you explained more about the H-bridge circuit? How the configuration to design this circuit?
Please have a look at some good circuit books, or look for some H-bridge drivers like Harris/Intersil HIP4080A. The datasheet explains it all.


CU
 

kengloong

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stp60nf06 mosfet defective

My UPS now is working only after I replaced the Power MOSFET STP6NF06. Now I faced another problem that is when my UPS on standby, it's able to supply 240VAC in output.

When I switched off the incoming supply, the UPS's battery backup able to backup 240VAC without any load. When I switched on my computer, it's backup only for few seconds. Why this was happen?

Hope someone could help.
 

pit

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kengloong said:
When I switched off the incoming supply, the UPS's battery backup able to backup 240VAC without any load. When I switched on my computer, it's backup only for few seconds. Why this was happen?
What happens if the computer is already running and the mains is removed from the ups? Maybe the ups is too weak to supply the inrush current of the computer. Did you connect a CRT monitor to the UPS and switched it on, too? The degaussing of CRT monitors uses a short high energy load some weak UPS cannot supply and therefore switch off.

Another possibility is that the battery is not fully charged. Observe battery voltage during battery operation. If it drops well below 1,8 V per cell after a few seconds the battery is not charged, or it is faulty.

*** WARNING ***: depending on UPS the battery contacts may have direct connection to mains potential! Apply caution when measuring live circuits!!!


CU
 

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