A maker of lens cleaning solution, located near Toronto, Ontario, has a strictly controlled manufacturing process which requires a clean room environment. Motor-driven blowers are used to maintain positive air pressure in the clean rooms.
Their facilities were experiencing a dozen or so power disturbances annually that adversely affected production. Even slight voltage sags caused the blower motor contactors to drop out, stopping the motors. Continue reading
Traditionally, substation transformer protection was provided by relayed circuit breakers or circuit-switchers, power fuses, or relayed-remote fault-interrupting schemes. Relayed protective schemes required an expensive substation control house and station batteries. Power fuses can only be applied where the continuous and fault interrupting currents are within their more limited capabilities. A new transformer protective device was developed to address the short-comings of traditional protective measures. The device has high interrupting capacity similar to circuit breakers, and higher continuous current capacity than fuses. But, like power fuses, the new device derives power for fault sensing and tripping from the fault current itself — a relay control house is not required and the need for batteries and associated maintenance is eliminated, providing the most economical protection possible. Unlike power fuses, separate secondary neutral current sensing can be applied for more sensitive protection against ground faults and three-phase tripping is possible, even for single-phase faults. Continue reading
Utilities are faced with the considerable challenge of providing an alternate source for increasing numbers of power-sensitive customers. In the past, this meant that an additional feeder, with sufficient capacity to meet the customer’s demand, had to be routed to the customer’s site, often at considerable expense. Or, alternatively, valuable capacity had to be reserved on existing lines. Either way, the customer is faced with higher service costs, which may lead them to seek another provider or another location which better meets their financial needs . . . sometimes not in the power provider’s territory. Continue reading
In April 2003, a wind turbine manufacturer contacted S&C regarding the availability of 38-kV switchgear suitable for switching and protecting their wind turbine generating towers. Eighty one-way units were required for a large new windfarm located in Wyoming. The caveat: the gear had to fit through a 23 x 54 inch doorway located in the base of the tower.
Although no product currently available met the dimensional requirements of the application, S&C’s Metal-Enclosed Gear Products Division explored the possibility. In remarkably short turnaround time, they designed a special type of Vista Underground Distribution Switchgear that met the size needs. Continue reading
S&C is pleased to announce the availability of a 138-kV Mark VI Circuit-Switcher specifically designed for switching single or back-to-back ungrounded capacitor banks up to 95 MVAR. This new model features a high 31.5-kA fault-interrupting rating and 3-cycle interrupting time. It utilizes interrupters that have been specially modified to withstand the TRVs associated with ungrounded capacitor bank switching at 138 kV, along with specially modified operating mechanisms. Continue reading
The Montrose Harbor Electrical Vault, owned and operated by the Chicago Park District, fell victim to a catastrophic circuit breaker failure which resulted in an explosion and devastating fire. The vault had been served by two incoming sources connected to exposed overhead bus. Each source supplied four feeders. A tie switch allowed either source to serve both sides of the vault.
After the fire, the south side of the vault was completely inoperable and several critical loads were without power. The only way to restore to these loads was to reconfigure downstream feeders and supply the entire load from the north side of the vault. Since the north side of the vault also experienced fire damage, it was extremely important to restore service to both sides as quickly as possible, before further damage could occur. Continue reading