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Unformatted text preview: DISTRIBUTION EQUIPMENT
• These are electrical apparatus, which help in running out of
distribution lines over long
distances from substation. also help
in; • -Identifying the electrical line fault. cont •Sectionalizing during maintenance
•-Transfer of loads incase of
breakdown / shutdown of a
•-Improvement of line voltages
• -Connecting a new HV line
• -Introducing a new substation (GMT or pole mounted) among others lines
constructed as overhead lines or
underground cables – distribution;
crossing of 66kv or 132kv –
underground preferred CONTINUATION
OCB – Oil Circuit Breakers. Uses oil
to quench the arc between the
contacts-located within the
start point of the 11kv feeder.
– A.C.B – uses air for the same, e.g.
sulphur dioxide. (sf6 gas)m • cont – OD Unit – Oil immersed unit (switch);
has three modes i.e.
– SERVICE,OFF,EarthPositions ,
-VL Unit – Has oil immersed fuse –
switch has an auto mechanisms
Operates to open a switch when
powder fuses blows hence latches the mechanism cont
-VL Unit – Has oil immersed
fuse – switch has an auto
mechanisms Operates to
open a switch when powder
fuses blows hence latches the mechanism WHERE THEY ARE USED
) O.C.Bs- Incomer protections and feeder • i protections for 11kv and 33kv line to
interrupt breaker in case of a fault. Isolate
the healthy ones from the faulty circuit
• ii) A.C.Bs – Used for bus bars,
transmission lines sometimes on feeder
protection and capacitor Banks
protections. As (I) above more expensive
• • Fuse mounts- withdraw able units installed on spur lines and transformer.
The units carries fuse elements that
protects the equipment against high
• Taplin Isolators – Installed on spur lines to
produce flexibility during maintenance
• OYT- Oil (11kv) tripper – used for long
distribution line; has ability to sense
faults ahead; trips three times and opens
the section ahead
• OYS – Oil (11kv) sectionalizer; operates
under dead condition and installed ahead
of OXT. If the fault is ahead of OYT, OYS
opens the section ahead of it and OYT
• FTU/ Others- Fault tolerance unit – assist cont
• iii) OD Units- Used at customers side (connection) –end of 11kv cable.
Sometimes with VL unit (RMU) With
oil to quench the arch.
• iv) R.M.U – Ring Main Circuit (unit) –
similar to OD but has VL unit for
transformer protection cont
• LINE – EQUIPMENT: (DISTRIBUTION). SECTIONALIZERS:
• Equipment installed along the line to
assist in locating faults whenever they
occur along the system. They are either
manual or automatic
• They include; Fuse mounts;Taplins
Others;AVRs;OXT continuation –TX- This is a transformation equipment from;
– 11kv / 0.25kv;
– allows customers to be supplied with the required phase voltages. Can
be; •single phase; three phase • Has; windings, oil and tap changers, also has
• -11kv bushings
• -lv bushings cont
• For the customers to be connected there must be a transformer of either
transformation i.e.; 33kv / 0.433kv; 33kv
/ 025kv;11kv / .433kv;11kv / 0.25kv
• ratings are; 200kva , 315kva, 50kva,
100kva, 25kva, 15kva, 5kva,
• Generally each domestic customer is
rated at 3kva up to 8kva;commercial is
beyond this value. continuation • – RMU- Ring Main Unit – Houses VL for
– TX- This usually a step –down 11kv /
0.25kv, 11kv/.0433kv equipment
which allows customers to be
supplied with the required phase
voltages. Can be;
•three phase cont
• Has; windings, oil and tap changers
• For the customers to be connected there must
be a transformer of either transformation i.e.;
33kv / 0.433kv; 33kv / 025kv;11kv / .
433kv;11kv / 0.25kv
• ratings are; 200kva , 315kva, 50kva, 100kva,
25kva, 15kva, 5kva SURGE DIVERTERS •These are units that are installed on transformers and
high voltage cables. Do divert
any excessive current and
direct it to the ground .The
unit is connected on the lower
side to the earthed structure. Importance of these equipment
in operation of the system.
• Assist in handling problems of customers
on matters associated with power
• Clearing well any queries related to dim
lights. Particularly domestic customers.
• Better knowledge on maximization of
• Frequent power blackouts due to blown
fuses & taking necessary action. • cont
• make the customer understand need for shutdowns.
• Update the customers on new developments to
perfect the supply.
• Assist in faster solving of customers problems
on the site to satisfaction.
• Co-operation with the customers in order to
• Letting them understand the need for company
to maintain the set standard and specifications.
E.g 600m for the furthest connection. cont
• Importance of reporting fast any fault at customers premises to avert danger.
• Precautions the customer should take incase
of a fault associated with any nearby
• Improves the customers-company’s
employees relationship hence understanding
customers complains .
• Respond first to customer & act to restore
power. • FEEDERS-These are power lines which emanates from primary and
distribution substations. Those which
emanates from primary substation are
referred to as primary feeders while
those from distribution substation are
called distribution feeders.
• Primary feeders are usually those
lines which transmit power from one
primary substation to another. •
• Their ratings are 200kv,132kv,and
Distribution feeders are the ones which deliver power to the secondary
transformers which serves the
Their ratings are 33kv and 11kv.
• Main feeders are those lines which
transmit or distribute power directly
from the source transformers. • Any other line which tap power from
these main lines are referred to as
spur lines. ...
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- Spring '18
- Professor Obura Oluoch
- Electric power transmission, Electrical substation, RMU- Ring Main Unit, OYT- Oil