1 - HT Panel:

HT panel is used for distribution of 11 KV / 33 KV power supply.The HT power supply is received from GO switch and distributed to the transformer.

2 - HT Panel Connection Diagram:

3 - Important Components of HT Panel:

1- Measuring Meter.

Measuring meters are used for measuring the system parameters like as volt meter, amp meter, multifunction meter etc.

2- Protection relays.

1- Over current and earth fault (IDMT) relay :

Protection relay is used for HT panel safety which is installed in HT Panel as different types like as OCR and earth faut relay.
If the fault current is high than trip time will be minimum. If the fault current is low than trip time is high or adjustable as per requirement.Now a days it is available in digital type numeric relay with 3 phase and over current relay.
It has 2 no’s functions available. One is 3 phase over current relay and earth fault relay in HV system. It is best for using in overhead feeder and underground feeders.
It is microprocessors based with wide range field.it can be controlled with different characteristic of trip time. It has also time delayed selected program for over current and earth fault relay.
What is the over current and earth fault relay, working principle and connection diagram?

2- Trip circuit supervision relay:

The trip circuit supervision relay is a monitoring relay and it is known as numerical name 96 S. it is used for continuous monitoring of breaker trip circuit healthy or not healthy in HT panel in any premised or substation. If the trip circuit will not ok then it will provide an alarm for avoiding any fault.
In an electrical panel trip circuit of the circuit breaker is very important and critical. During fault condition If the trip circuit did not find any trip sensing than breaker will not be disconnected and resultant by this problem may be very loss.
So, keeping the trip circuit healthy the TCS relay is used so that system always remains healthy. What is the trip circuit supervision relay, working principle and connection diagram?

3- Master trip relay:

Master relay is not a monitoring relay. It is used as an isolation in protection relay and breaker trip coil. it is used in HT Panel for safety of monitoring relay. It is received multiple commands from protection relay and then a single command is received by breaker trip coil from master trip coil.
What is the Master trip relay and why master trip relay is used?

4- Auxiliary alarm and trip relay of 3 way (OTI, WTI, Buchholz).

Auxiliary relay is used for transformer protection like as oil temp, winding temp and Buchholz.it is used in HT panel as 2 types as one is alarm and 2nd is trip protection relay. The fault alarm is received from transformer relays and it will provide to master trip relay and annunciator panel and hooter.

5- Restrict Earth fault relay:

Restricted Earth Fault relay is used for protection of an earth fault from Restricted zone. It is used transformer HT side. Restricted earth fault relay is used for Transformer grounded faut in HT side. What is the Restricted earth fault relay, working principle and connection diagram?

3-Annunciator Panel:

An annunciator panel is known as the Centralized Warning Panel (CWP) in electrical system. It is a group of lights of an indicator. We can get status of equipment by this. When occurs abnormality than it receives a fault signal from equipment than resultant according fault light indicator will be blinking and also hooter activated. It provides us an attention for faulty equipment.

4- Indicators:

Indicators are used for knowing the status of panel operation.Difference type indicators are used with different color.

• R Phase.
• Y Phase.
• B Phase.
• VCB/GCB ON.
• VCB/GCB OFF.
• Auto Trip.
• Spring Charge.
• Trip Circuit Healthy.
• DC Supply Healthy.
• (SF6) Pressure Low.

5- Circuit Breaker:

Rating of circuit breaker (400A,630A,800A,1250A,1600A,2500A). Circuit breaker is used in HT panel for making and breaking off HT power supply. HT panel has 2 section one is incomer and 2nd is outgoing.

1- Vacuum circuit breaker (VCB):

This breaker is used in HT panel. It is works as a switching device manually or auto. IT is used for control and protect of Electrical system from overload and short-circuit. Which breaker the vacuum is used as arc removing medium that breaker is called as vacuum circuit breaker. What is the VCB- Vacuum circuit breaker, working principle and connection diagram?

2- Sulphur hexa floride (SF6)

SF6 Circuit breaker is used in HT panel for switching and controlling the power supply from overload and short-circuit. Sulphur hexafluoride gas is used for arc quenching as medium of insulation. it is called as SF6 circuit breaker. What is the SF6- Gas circuit breaker, working principle and connection diagram?

6- HT CT PT:

CT and PT are used in HT panel which is CT is used for incomer and every outgoing section for current measuring and PT is used in incomer for voltage measuring.

1- Current Transformer: -

A Current Transformer (CT) is an instrument transformer. It is used for providing a current in the secondary winding. This secondary current is proportional to the primary alternating current which is passing in the primary. Secondary winding current is as low current as 1-5 ampere with the same ratio in the primary. CT Capacity: - 50 A to 2000 A /5-5A What is the HT CT, working principle and connection diagram?

2- Potential Transformer:-

A potential or voltage transformer is used for measuring the high voltage of the HT line or HT panel. It is called an instrument transformer. It converts high voltage (11, 33 KV) - into low voltage (110 Volt). These 110 voltages can be measured by voltmeter and they can be used easily in protection relay and another control circuit.
PT Capacity: - 11-12 KV/110 V,33-36 KV/110 V What is the HT PT, working principle and connection diagram?

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