Meramec Instrument Transformer Co

Board Mounted Bushing-Type Generator Current Transformer

Application:

The Bushing-type Generator current transformer is designed to be mounted over the high voltage terminal bushing of power generators. The Bushing-type GCT may also be used on Isolated Phase Bus (IPB) on higher system voltage levels while maintaining its own mere 600 Volt class rating. Its simple construction provides a low leakage product with extremely high short circuit capabilities. Because of its open construction it can easily be designed to suit any custom mounting footprint and offers a lightweight alternative to bulky cast units. A major benefit this design offers is a quick turnaround during a forced emergency outage.

Construction:

The toroidal core is continuously tape wound using cold rolled grain oriented electrical grade silicon steel, which receives a full stress relief anneal after it is wound to its specified dimensions. This insulation system provides a durable 155°C (Class F) system throughout the entire coil assembly. The secondary winding is wound of insulated copper magnet wire over the fully insulated core with the turns equally spaced around the core periphery. Specially engineered shield windings are strategically integrated into the main secondary winding to minimize the affects of stray magnetic flux from adjacent high current conductors. The finished insulated coil is firmly secured to a high strength, non-magnetic mounting board. Though an open type construction, it will endure light water spray and rigorous vibration.

Connections:

The primary polarity H1/P1 is engraved into the mounting board. The secondary terminals are ¼-20 silicone bronze studs provided with hex nuts and cupped washers for positive compression to assure long lasting connections. Terminal identification is permanently engraved with dual designations “X” and “S” for compatibility in the global market. The X1/S1 terminal represents the instantaneous polarity reference with respect to H1/P1 and will be identified by a colored dot. A cast aluminum conduit box with (2) 1” NPT hubs and blanking plugs is provided with a removable cover. The size of the box allows for adequate passing of wires from adjacent phases. Other hub openings up to 1.5” NPT are also available.