Distribution problems.

Hello Guest,

I am attempting to answer your questions.

Please advise if I have interpreted your problem incorrectly.

<".....see the diagram"> = ????: You have omitted the diagram.

<"We are using 11Kv/440 v distribution system"> = HT Supply to transformer voltage is 11kV, and your Mains voltage is 440/240Volts.

<"We are mostly using our loads all Electronics example (AC Digital controllers, Plasma TV, Digital Light Dimming system and exact……). So due to this ourLoads getting burn.."> = Some things are getting burned out, due to undervoltage.

<"We have problem Y phase and B phase only.."> Only those phases of the transformer secondary mains supply are affected.

<"We don't have any problem in R phase."> = That phase is quite OK.

<"Our Voltage analyzer meter showing Neutral to Earth has 220Volt. "> There should not be any Voltage between Neutral and Earth, perhaps you have made a typing error there..

V"This voltage

Only getting few second not always example some time taking two or three days." = 220 Volts as Phase to Neutral on a 440 Volts per phase system is too low - Voltage should be 240 Volts/phase to neutral for your system. It seems the problem is intermittent, and occurs some days apart.

<"Now we are checking the cablings and panels. We can't found any thins still now?"> = You have checked all Cabling, Switchboard panels. You have found nothing wrong.

<"Do you have any information about problem?">

Are you experienced to do testing on the 11kV system?

My suggestion is that you may have an intermittent fault on a single High Tension Phase on the 11kV side of the transformer.

This could be a partial failure of HT Supply from the electricity provider, HT fuse or HT Circuit breaker, or within the transformer itself, on the Primary side.

If you are unable to shut down the transformer, you should have 3 phase 440 Volt alternators for emergency supply to run the hotel.

I would carefully check your switching arrangements, and run that emergency alternator system, ensuring that there can be no feedback into the transformer secondary.

Once you have done that, isolate the transformer, placing earth stick connections onto the primary and secondary cables of the transformer, disconnect the cable connections at the transformer, and ensure any control circuits, Current transformer connections and tap-changer connections are properly disconnected for safety and testing of the transformer..

Using a Kelvin Bridge, carefully check the transformer windings and connections, note down the DC resistances very carefully, and compare each phase of the Primary with the other Primary phase resistances - they should be almost identical, to several decimal places.

Repeat the Kelvin Bridge Tests on the Secondary, compare phase readings, which should also agree within several decimal places.

Using a 5,000 Volt Megger, or similar Insulation tester, test the 11kV primary windings to Earth (Transformer case) - (ensure each winding tested for 5 minutes). There should be extremely high DC resistance, almost infinity.

Using a 1,000 Volt Megger, or similar Insulation tester, test the 440V secondary windings to Earth (Transformer case) - (ensure each winding tested for 5 minutes). There should be extremely high DC resistance, almost infinity.

OK, now check your tap changer on the transformer, (if you have one) - You should have a manual supplied with the Transformer to show you the test sequence.

Once you have tested Transformer and (tap Changer) and proved that OK, and the hotel runs OK with no problems on the Standby Alternator, you have proved that Alternator, Transformer, Tap Changer, Cabling, Switchboards are OK.

That leaves a possible intermittent failure of a single 11kV phase: Fuse, Circuit Breaker.

Are you experienced to do testing on the 11kV system?

Is the Hotel 11kV supply from another Supplier? - If so, the problem is proven to be their problem, and you need to ensure they quickly locate the fault in their system, and repair it, before further damage occurs to hotel and guests equipment.

Advise back here please, with your progress.

Kind Regards....

Check your load to see if its heavily unbalance.

check transfermer to see if one phase short circuit.

check your neutral line to see if it breaks.

[everyone of us agree, there must not be voltage on it]

check your leakage electric protector.

so high is your equipment and appliances. ours ' is only 220v. only industrial equipment like motor etc use 380V.

If you cannt scann the diagram, take a photo , so that we can analysis for more details.

pls remember, neutral point cannt have any voltage!