Answer / asif.k64@gmail.com

Ring mains unit - RMU mainly used to provide dual supply to
a building, in case one supply fails building can be fed
through a stand by supply, change over usually happens
automatically.
It usually is on the HT side, and consist of a dry type of
transformer and protection system, In order to disconnect it
you should first close the incomer of HT breaker through
which RMU is fed.

Wait it's not over yet, you should ground the Incomer and
outgoing terminal of RMU to insure safety.

Answer / vijo

RMU means RING MAIN UNIT

Answer / apu basak

Ring Main Units
Switch the load break switch into EARTH position with an
operation lever. As direct conversion into EARTH position
from ON position is impossible due to its mechanism that it
should be switched first to OFF position before the conversion
into EARTH position.
Only when load break switch is located at EARTH position
doors can be opened or closed.
In case any one of doors is opened, mechanism operation hole
is closed. Thus load break switch operation is impossible,
which means switching to ON position is not allowed
When the works such as replacement of fuse and cable repairs
are finished, all doors of fuse compartment, cable
compartment and cable test facility should be closed before
operation of LBS. The operation order to switch on is EARTH
→ OFF → ON.
Each door is to be pad-locked to avoid unintentional opening
that may cause accident

If single phase supply is 220v. then why three phase supply is 660?

2 Answers  

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how many test is necessary for 27mva transformer.

3 Answers   HEG,

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why 3phase is 440v but where as we get phase voltage 220v,we have to get 220*3=660v.can u pleas give in detailed

3 Answers   Avantha Group,

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Can we use delta-star neutral grounded 3 phase power transformer bi-directionally.

2 Answers   GMR,

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what is the difference between star and delta connection?

3 Answers  

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Re: can you give main difference between ELCB 2pole And RCCB 2pole? And how this devices operated?

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what is meant by surge? what we called for high currents?

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Pls any send the cable selection chart. at azeemk30@gmail.com

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i have a 4 Mva transformer 34.5 kv / 480-277 v and i used 2 parallel 3200 amp bus duct for the secondary feeder using 3 ply of bus bar ( 3/8" x 5" ) as a common where the flexible link terminated and 6300 amps breaker for the main, the lower bus duct reaches 70 degrees and the upper bus duct reaches 55 degrees when i used thermal scanner. why the temperature is not balance when the load reaches 3600 amps.

0 Answers   SCM,

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what is power factor?

3 Answers  

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