HT Panels
HT panel is a metal enclosure fitted with HT Circuit Breakers, relays & metering that is used to receive 11KV/33KV supply (from one or more source) & distribute the power through its outgoing feeders. Outgoing feeder may be one or more it depends on the load of the building.
Full form of HT panel is High Tension Panel. It is installed in Electrical substations of Commercial complexes, residential colonies, factories, schools, hospitals etc. to receive & distribute HT supply.
Features:
- Short circuit protection, over load protection, earth fault protection relays can be installed in it against protection from faults.
- HT circuit breakers can be switched ON & OFF either manually or electrically.
- Space heater is provided in HT panel to avoid moisture inside the panel.
- To measure Incoming Supply voltage, 11KV is converted into 110V through PT (Potential Transformer). And 110V voltmeter is used for voltage measuring purpose.
Working of HT panel
HT panel in electrical system is a switching point where HT supply can be connected or disconnected with load. HT cables are connected to circuit breakers from incoming side & outgoing side also. HT supply can be switched on or off by operating electrically operated switch (or by using push button of the breaker). When supply is ON, metering system starts measuring/recording electrical parameters (depending on the panel design).
HT panel provides protection also from various faults (depending on the fault protection relays installed in the panel). When fault occurs in the system HT panel is switched off automatically (this process is also known as tripping). Each relay gives fault indication when it operates. Before switching on HT supply again, fault should be identified & rectified. If fault persists in the system, then relay will not be reset & HT panel can’t be switched on because of interlocking between relay & panel. Therefore, it is very important to clear the fault first & then switch on HT supply again.
Safety requirement:
- One SLD must be installed in HT room which must contain incoming & outgoing feeder details of the building.
- Suitable voltage rating (11Kv 33KV) of hand gloves should be available in HT panel.
- Panel keys should be available at suitable location in HT panel room (very close the HT panel).
- HT panel room should be locked in case no manpower is available in it & key should be kept at suitable location.
LT Panels
LT panel is a metal enclosure fitted with ACB, MCCB, MCB, metering, relays that is used to receive 415V supply (from one or more Transformers & DG Sets) & distribute it to various loads.
FEEDER
Feeder is a section of panel which connects electrical source/power with load through cables or bus ducts.
INCOMING FEEDER
It is the section of panel where electrical power is received by ACB/MCCB/MCB from source like transformers or/and DG sets& connected with outgoing feeders such as ACB/MCCB/MCB through internal bus- bars. The capacity of Incomer feeder should always be more than all outgoing feeders of that panel.
OUTGOUNG FEEDERs
It is the section of panel where load/sub panel is connected though cables etc.
BUS-BARS
Bus-bars are made up of either Aluminum or Copper (Al or Cu). These are of rectangular in shape. Incoming & outgoing feeders are connected through these bus-bars. The capacity of bus-bar depends on the load which is to be connected with it.
CABLE ALLEY
This is the section of the panel where cables (incoming/outgoing) are connected with panel feeders.