Substation Transformers

Low Voltage Bushings – Low Voltage output points

• Location: Usually located on either end of the transformer tank
• Layout: Insulated bushings typically marked X0, X1, X2, and X3.
• Function: Provides a secure and durable connection for delivering power to downstream loads.

Low Voltage Neutral Bushing – Provides a method for grounding the low voltage winding either by direct ground or through a resistor for ground fault control.

• Location: Usually found on the top of the transformer on the low voltage bushing side.
• Layout: Single insulated bushing designed for neutral conductor attachment.
• Function: Stabilizes the system by providing a neutral return path for current and ensuring safe grounding.

Tap Changer – Used to match incoming voltage and adjust outgoing Low Voltage 

• Location: Usually mounted on tank wall.
• Layout: Rotary switch clearly marked with tap positions – usually 5 or 7 positions – for voltages, refer to nameplate.
• Function: Provides flexibility in operation by compensating for variations in line voltage, ensuring consistent service.

Standard Gauge Package – A combined monitoring assembly integrates vital indicators for transformer health and safety.

• Location:  Positioned externally on the transformer tank,
• Layout:  Includes a liquid temperature gauge, pressure relief valve, and oil level gauge or sight gauge.
• Function:  Provides real-time visual monitoring of internal temperature, oil level, and tank pressure.

Pressure Relief Device – Used to automatically vent excess internal pressure caused by a transformer event or fault, to prevent catastrophic damage to the transformer tank.

• Location: Usually mounted on the cover of the Substation Transformer
• Layout: Spring-loaded diaphragm or valve with a directional exhaust port.
• Function: Prevents tank rupture by releasing excess pressure in abnormal operating conditions.

Rapid Pressure Rise Relay – The RPRR is designed to operate in conjunction with the Pressure Relief Device, except that it very quickly 

• Location: Usually mounted on the side of the Substation Transformer
• Layout: Sealed Relay in waterproof housing.
• Function: Detects rising pressure in a transformer tank, and signals controls to open the relay feeding the High Voltage to the transformer.

Control Panel Cabinet – The local control panel houses controls, indicators, and relays for transformer operation and protection.

• Location: Mounted on the side of the transformer tank
• Layout: Pad-lockable Waterproof enclosure.
• Function: Provide a sing common place for the termination of all control cabling, relays and fan controls.

Radiators dissipate heat from the transformer’s insulating oil to maintain safe operating temperatures.

• Location: Attached externally along the transformer sides.

• Layout: Multiple finned panels or tubular sections bolted to the tank.

• Function: Facilitates oil circulation and heat exchange, ensuring efficient cooling.

Drain Valve – Designed for safe oil management during maintenance or fluid sampling.

• Location:  Installed at the bottom of the transformer tank.
• Layout:  A threaded valve assembly with an accessible outlet.
• Function:  Allows controlled draining or sampling of insulating fluid to support testing and servicing.

Grounding Provisions – Provides various acceptable safety grounding points

• Location: Grounding provisions are placed in various places, both inside the cabinet in the high voltage and low voltage air terminal chambers and on the external tank surfaces.
• Layout: Grounding Provisions are always welded to the steel parts of the transformer.
• Function: Used to bond the transformer to a system ground, system neutral and/or insulated conductor drain wires for personnel and operational safety

Low Voltage Air Terminal Chamber – Protective enclosure designed to completely surround the low voltage bushings for safety and environmental concerns.

• Location: A box enclosure creating a compartment and surrounding the low voltage bushings
• Function: Protects low voltage connections while ensuring accessibility for wiring.

High Voltage Air Terminal Chamber – Protective enclosure designed to completely surround the high voltage bushings for safety and environmental concerns.

• Location: A box enclosure creating a compartment and surrounding the high voltage bushings
• Function: Protects high voltage connections while ensuring accessibility for wiring.

Nameplate – Also known as Data Plate is installed on all transformers for identification

• Location: The metal nameplate is permanently affixed to the surface of the Substation transformer
• Function: Provides all essential specifications and electrical data required for safe installation and operation of the padmount transformer.