POLYMER CURRENT LIMITERS - AFFORDABLE PROTECTION FOR THE NAVY ELECTRICAL AND ELECTRONIC COMPONENTS

Electrical equipment aboard Navy ships is currently protected by curre nt Limiting fuses which provide reliable protection against high fault currents. Fuses, however, must be replaced after each fault event. Wh ile individual fuses are relatively inexpensive, the aggregate costs o f replacing large numbers of them lie in the millions of dollars. Furt hermore, the manpower and time required to replace blown fuses are als o expensive. This has led us to investigate the use of modern current limiting elements to replace fuses. In the past, the excessive cost, s ize and weight of current limiters prohibited their widespread use. Ne w studies show that the emerging polymer current limiter (PCL) technol ogy will effectively limit fault currents while reducing life cycle co sts. This advantage arises because of the self-resetting capability an d inexpensive procurement costs characteristic of PCLs. The protection performance and the cost advantages of polymer current limiters are d escribed here in the context of use with distribution and load equipme nt. We also outline the operating mechanism of PCLs and strategies for using PCLs to improve coordination between circuit breakers. Finally, an application of PCLs as protection for solid-state devices such as Silicon Controlled Rectifiers (SCR) and MOS Controlled Thyristors (MCT ) is considered.