T&D World Magazine

Three-Phase Vacuum Fault Interrupter Incorporates Microprocessor-Based Relays

Based on Trayer Engineering's original VFI design introduced in 1980, the 3000 Series three-phase vacuum fault interrupters take this design and incorporate the latest advancements of vacuum technology and microprocessor-based relays. The Trayer 3805/3815 Series represents its double-side access pad-mounted units, combining switch and vacuum fault interrupters in standard common configurations such as 9s, 11s, and 12s.

The footprint and bushing design of the 15 kV/25 kV units are sized to make an easy retrofit conversion from live front air-insulated switchgear to sealed dead front using the existing box or pad installation.

Switch or VFI ways can be ordered as either 600-A or 200-A ways. Every switched or VFI way comes with brackets that accept linear actuators for future SCADA operation. Trayer’s interlocking handle design on the tri-phase visible disconnect device supplies an extra measure of safety when operating Trayer switchgear. This optional device provides a visible and safe isolation point to work on the circuit or test the cable without the need to remove any cables.

An internally mounted and fuse protected potential transformer provides 120 VAC control power whenever the source cables are energized. Trayer also provides provisions for 120 VAC shop power input to the control cabinet for testing and verification of the relay settings and operational testing of the VFIs before going out for installation. The potential transformer output power is also available for future SCADA applications. The CTs are internally mounted and provide current monitoring for the relays.

Relay options include a wide range of microprocessor type relays. The SEL 501-2 is a Trayer standard.

Trayer Padmount VFIs are available with liquid or SF6 insulation and are constructed of 304 stainless steel, requiring zero maintenance for use in the harshest environments.

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