UPS Maintenance

UPS Maintenance

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One reason you should have your UPS serviced regularly – Capacitors in UPS systems do fail


Fault-capacitor-Brisbane--CHigh quality capacitor producers all all over the world offer a capacitor service life score. The life span score is only a guide  and the number does not have enough

precision to be utilized as a predictor of when the very first capacitor in a bank of capacitors will fail.


Capacitor failure designs do exist and will produce a failure time for a certain failure rate however the number includes a huge variation and has a low self-confidence



Changing capacitors occasionally is the only method to guarantee a really high MTBF.

for capacitors.


All UPS systems  experience in service ageing of their power components and left unattended can

and can trigger UPS systems to move offline, or to a bypass source and create a very expensive repair or total replacement


All UPS manufacturers have power components that age and a guideline for replacing them, however it is a guideline and ocasionally they fail sooner rather than later

An experience UPS technician knows the signs to look for when servicing to prevent UPS failure.


Typically an online UPS will have 5 main components


  1. At the input it will have an AC filter
  2. The filtered AC is converted to DC via a rectifier
  3. A large battery bank and a DC capacitor bank for the DC bus, DC filtering
  4. A DC to AC power inverter
  5. An AC filter at the output


So we have both AC and DC capacitors


Failure mode for an capacitor found in an uninterruptible power supply.


Both capacitor innovations age by losing capacitance and establishing thus greater internal resistance.


If this procedure is permitted to continue, a point will be reached where the capacitor will fail into a short circuit and will lose the capability to hold up against the statedAC cap Mine Central Queensland


concerned about your uninterruptible power supply, give us a call 1300 378 884

In addition the capacitor ageing procedure likewise creates gas which increases the internal gas pressure in both capacitor building and constructions.


The polymeric film capacitor has a pressure interrupter developed into the case and when the pressure reaches a predetermined value, the interrupter opens within the capacitor

case and detaches the capacitor from the circuitry. The pressure interrupter design for huge polymeric film capacitors are based upon a notched wire which bursts .


When the pressure interrupter runs, the capacitor case bulges up and is  noticeable to the trained eye suggesting the capacitor has actually reached end of life and is not in

the circuit.

Other pressure interrupter designs are utilized around the globe however they all open under pressure and detach the capacitor from the circuitry.


For DC aluminum electrolytic capacitors, the increase in pressure rises a rubber bung at a pre set pressure.



Will regular UPS maintenence and servicing decrease the chance of catostrophic failure and lost production time?


Ageing capacitors can be spotted during maintenance.

Both DC electrolytic capacitors and AC polymeric film capacitors consist of gadgets which broaden due to gas generation as the capacitor ages

all the swelling happens around the cover which can be seen.


Usually the capacitors can that are failing can be spotted and replaced before any damage to the UPS systems presuming the service intervals are regular.

Brisbane-Airport---UPS Capacitor failureIt would be usual to replace the entire capacitor bank when one capacitor has actually experienced substantial in-service aging as capacitor ageing for capacitors within the.

very same UPS system (capacitors within a capacitor bank and for that reason exposed to the very same ageing conditions)


When a couple of capacitors reach the end of their life by operation of the pressure interrupter, other capacitors in the bank can see enhanced tension and speeding up aging.

As soon as the very first capacitor in the bank has actually failed the likelihood of added failures is high.