CSP Circuit Breaker - Three Phase

Three phase CSPtype distribution transformers require an internal three phase “CSP” breaker for proper operation. P&A manufactures a full line of three phase breakers; these are designated as the “R” series (LR, SQR, LQR and HQR) All have been designed for service under oil within the distribution transformer. The circuit breakers can handle continuous loads up to 1000 amperes and 480Y/277 volts.

The CSP breaker is connected to the transformer between the low voltage winding and the secondary bushing’s internal terminals (please refer to the schematic diagram shown in Figure 1). The connections are made so that the secondary load current flows through both the breaker bimetal and contact. This is necessary to properly monitor the secondary transformer current and load levels.

The breaker is available with two auxiliary features: a signal light contact and an emergency control setting. The signal light contact is connected into the signal light circuit and is used to provide an early warning of transformer overload. The signal light operates on approximately 4 to 6 volts (14 volts optional), picked up by an auxiliary winding of consisting of one or two turns through the core. (The signal light contact is an optional feature of the circuit breaker and should be specified, if desired). The emergency control mechanism is a mechanical linkage inside the breaker which moves the breaker to a higher calibration of the temperature setting when placed into the emergency position. (This is also an optional feature and should be specified, if desired)