1. Field of the Invention
The present invention relates to the field of electrical devices. More specifically, this invention relates to a Transient Voltage Surge Suppressor (TVSS) comprising a disconnect switch.
2. Description of the Prior Art
Power surges are a common problem in home and commercial building electrical supply systems. A power surge, or transient voltage, is an increase in voltage significantly above the designated level in a flow of electricity. Surges or transients many times occur in bursts. In normal household and office wiring in the United States, the standard voltage is 120 volts alternating current (AC). If the voltage rises above 120 volts, it could result in damage to equipment in the household or commercial building subject to the surge.
Surge protectors are devices commonly employed to protect equipment from transient voltages. In normal operation, a surge protector does not interfere with the flow of electrical current from a supply source to a number of loads or electrical devices connected to the power supply/surge suppressor combination. If the voltage level rises above an acceptable level resulting in an unacceptably high current level, the surge protector diverts the high current away from the load. In the most common type of surge protector, a component called a Metal Oxide Varistor (MOV), absorbs the extra electrical energy thereby diverting the high electrical current away from the load. In many commercial building transient voltage protection applications, MOVs are used in conjunction with Thermal Cutoff Fuses (TCOs) to provide transient voltage protection. The TCOs are non resetting thermally sensitive devices wherein in operation, a thermal fuse melts and opens electrical contacts when temperatures exceed the rating of the thermal fuse. Most current applications comprise a TCO/MOV configuration of one TCO per two MOVs. While effective, such a configuration sometimes results in higher than desired occurrences of clamping (the triggering of the MOV to conduct electricity to ground). Moreover, in many applications conventional Transient Voltage Surge Suppressors (TVSSs) require that the electrical supply be shut off during repair or replacement of MOVs and/or TCOs. In applications such as in hospitals and the like such a shutdown of electrical power for maintenance can be inconvenient. It is desirable, therefore, to have a TVSS that can be maintained without shutting down electrical power and that can provide improved protection against transient voltage conditions.