Single Phase Pad Mounted Transformers

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
  compartments 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

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 padmount transformer, usually in the Low Voltage
  compartment.
• Function: Provides all essential specifications and electrical data required for safe installation and operation of the padmount transformer.

Drain Plug and Fill Cap – A drain plug and fill cap on a single-phase
padmount transformer allows access for fluid maintenance.

• Location: Positioned at the bottom (drain plug) and top (fill cap) of the transformer tank.
• Layout: Threaded openings with secure caps to allow draining and filling of insulating oil.
• Function: Enables safe oil filling, and with the addition of a Drain Valve, sampling, and draining for maintenance while preventing leaks and contamination.

Lifting Lug – A reinforced point used during handling and installation.

• Location: Welded on the tank cover or upper corners.
• Layout: Heavy-duty steel loops or Threaded Nuts to accommodate lifting bolts designed for crane hook attachment.
• Function: Provides safe and balanced lifting points for transport,
  positioning, and installation of the transformer.

Cabinet Lock – The cabinet lock on a single-phase padmount transformer secures the cabinet doors from unauthorized access.

• Location: Mounted on the Cabinet Door
• Layout: Padlockable handle mechanism, often interlocked with a Penta Head safety locking device.
• Function: Ensures tamper-resistance, controls access to internal compartments, and improves safety.

Liquid Level Gauge – Used to monitor Liquid Level

• Location: Mounted on the tank wall usually in the Low Voltage compartment
• Layout: Circular gauge with float or glass indicator
• Function: Provides a quick visual check to confirm proper fluid level.

Pressure Relief Device on a single-phase padmount transformer protects against excessive internal pressure.

• Location: Installed on the tank cover or side.

• Layout: Spring-loaded vent with a visible indicator.

• Function: Vents gases or pressure buildup caused by faults, preventing tank rupture and enhancing safety.

Tap Changer – Used to match incoming voltage

• Location: Usually mounted on cabinet wall in High Voltage compartment.
• Layout: Rotary switch clearly marked with tap positions – usually 5 or 7 positions – for voltages, refer to nameplate.
• Function: Used to allow for incoming voltage differences and to maintain Low Voltage output voltage.

High Voltage Bushings – Insulated connection point for incoming high-
voltage supply cables.

• Location: On the wall of the High Voltage compartment
• Layout: Porcelain or polymer insulated bushing with conductor connection hardware.
• Function: Provides a safe and insulated connection point for high- voltage conductors into the transformer’s primary winding.

Low Voltage Bushings – Low Voltage output points

• Location: On the LV side of the cabinet.
• Layout: Clustered insulated bushings typically marked X1, X2, and X3.
• Function: Provides output connection points for secondary distribution (e.g., 120/240 V service).

Bayonet Fuse Assembly – Used to provide overcurrent protection

• Location: On the LV side of the cabinet
• Layout: Removable fuse holder with oil-immersed bayonet-style contacts
• Function: Interrupts the circuit under fault or overload conditions, protecting the transformer and distribution system.