Outdoor – walk-in – common isle substation

Outdoor – walk-in – common isle substation

Engineered and fabricated for one of America’s premier Urban Electric Utilities with a 12-inch base, topped by a stainless steel drip edge this house exceeds life expectations. Two identical Unit Substations facing each other across a common isle provides 100 % redundancy. Each unit sub contains a medium voltage section known as a TPPU (Transformer Primary Protection Unit).
This powerfully protective TPPU design was developed and evolved specifically for protecting transformers and the front ends of unit substations with an exceedingly compact footprint (only 4-foot square as shown).

Custom Walk-in Switchgear

The TPPU consists of a fixed mounted Citadel breaker that can have ratings up to 27 kV 5,000 amp, and 63 kA. The Citadel is then surrounded by one or two in-line, interlocked three (3) position (close-open-ground) visible disconnect switches. The primary path taps to a tilt style 3 – PT draw; then, in this case, feeds a cast coil transformer to low voltage gear.
Tilt style PTs may cost a bit more – but their safety, visual-ability, and operability are at a specifiable level beyond pull-out PT draws.
The switchgear boasts a wide range of protection – metering – controls and communications including;

Dual redundant 50/51/51G;
67 (directional overcurrent)
87 (dierential)
86 (lockout)
81 O/U (over/under frequency)
59/27 (over/under voltage)
32 (reverse power)
Over a year’s worth of multi programmable data logging
High speed oscillography
Sequence of events recording
Ethernet – DNP – 61850 ready
Dual back-feed / voltage present monitoring
… and much more.

Completely unique to this design is the “Herescu Accumulator”; A protective system conceived by Con Edison’s Mr. Alex Herescu for insuring transformer loading compliance.
We are very proud to have been selected as the company to engineer and fabricate this once in a lifetime substation opportunity.