Bus joint pressure plate

A bus joint pressure plate is used to maintain uniform contact pressure across busbar joints, ensuring low electrical resistance and reliable current flow.

Purpose and Function

Bus joint pressure plates are designed to distribute mechanical pressure evenly across the contact area of busbar joints. This is critical because the surfaces of busbars are not perfectly flat, and low contact pressure can lead to high localized resistance, excessive heat, and potential joint failure . By using a pressure plate, the risk of uneven pressure and localized hot spots is minimized, improving the durability and electrical performance of the joint.

Contact Pressure Requirements

Maintaining the correct contact pressure is essential. For aluminum busbar joints, an average contact pressure of 40–55 kg/cm² is recommended, while copper joints require roughly 150–200% of this value . Too little pressure increases resistance, while excessive pressure can cause cold flow of the metal, leading to relaxation and eventual loosening of the joint.

Design and Installation

Pressure plates are typically made of 5 mm thick galvanized steel and are supplied with screws, nuts, and washers for secure fastening . They are used in conjunction with bolts and washers to ensure the joint maintains the required pressure over time. Slotted holes in the plates or busbars allow for adjustment during installation, accommodating thermal expansion and ensuring a rigid, reliable connection .

Best Practices

• Clean and grease contact surfaces before assembly to prevent oxidation and reduce contact resistance.
• Use the correct number and size of fasteners according to busbar width and thickness.
• Avoid excessive torque to prevent metal cold flow and joint relaxation.
• Apply pressure plates for large bus sections to prevent localized high pressure and ensure uniform contact . By following these guidelines, bus joint pressure plates help maintain low-resistance, high-reliability connections in electrical busbar systems, which is essential for safe and efficient power distribution.