Can two small busbars be connected to one PT

Yes, two small busbars can be connected to a single PT, but proper jointing, protection, and load considerations must be observed.Electrical FeasibilityA potential transformer (PT) is designed to measure voltage at a specific point in a substation or switchgear. Connecting two busbars to a single PT is possible if both busbars operate at the same voltage and the PT is rated for the combined load and fault conditions . The PT essentially acts as a common voltage sensing point, so the connection must ensure electrical continuity and minimal voltage drop.Busbar Jointing MethodsWhen connecting two busbars to a PT, the joint must be mechanically strong and electrically reliable. Common methods include:Bolted joints: Overlapping the busbars and securing with bolts and washers to ensure uniform contact pressure .Taps or extensions: Using a T-shaped connection from the main busbar to the PT terminals.Flexible braided connectors: Useful for accommodating thermal expansion and vibration while maintaining low resistance . Proper jointing ensures low resistance, minimal heating, and long-term reliability.Protection and Operational ConsiderationsFault currents: The PT must be rated to handle the maximum prospective fault current from both busbars.Isolation: If maintenance or a fault occurs on one busbar, consider whether the PT connection will remain energized or if it requires isolation. Using isolators or circuit breakers in the busbar arrangement can help maintain safety .Accuracy: Ensure that connecting multiple busbars does not introduce voltage drops or phase shifts that could affect PT measurement accuracy.Practical Substation ConfigurationsIn single bus systems, all feeders and transformers connect to one bus, and a PT can monitor the bus voltage directly .In double bus or main-and-transfer bus systems, a PT can be connected to one bus, or a common PT can be tapped from both buses using a properly engineered connection, often with a bus coupler or dedicated isolators .SummaryConnecting two small busbars to a single PT is technically feasible if:Both busbars are at the same voltage level.The PT is rated for the combined load and fault conditions.Proper jointing methods are used to ensure mechanical and electrical integrity.Protection and isolation considerations are addressed to maintain safety and measurement accuracy. This approach is commonly used in small to medium substations or switchgear panels where space and cost constraints favor a single PT for multiple busbars .