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In the example, the EF curve coordinates well with the transformer

fusing, although instantaneous trip is required to extend

coordination with the upstream T-Link.

Optional Tri-Phase with ground trip control (TPG)

The optional TPG control operates under the same algorithm as the

standard Tri-Phase control for phase protection. In addition, the TPG

control has a separate zero-sequence circuit and settings for ground

protection. Settings for ground trip vary from 10A to 640A in 10A

increments, and are field selectable by the user.

In some applications, such as a switchgear tap that feeds both

underground and overhead feeders, the TPG control is necessary.

As shown below, the F curve achieves coordination with both the

phase and ground settings of the upline recloser.

Tri-Phase control accessories

Minimum response time

The minimum response time accessory is used to achieve coordina-

tion between in-line protective interrupting devices, located where

fault-level currents would normally cause simultaneous tripping.

The accessory inhibits tripping until a predetermined minimum time

has elapsed; available minimum response times are adjustable at

0.050, 0.100, 0.145, 0.205, 0.260, 0.335, 0.405, 0.495, or 0.580 sec-

onds. Refer to the example below.

Minimum trip multiplier

The minimum trip multiplier accessory allows the user to increase

the programmed minimum trip setting, to a predetermined alternate

setting, by operating a toggle switch. Typical applications for an

alternate minimum trip settings include: preplanned or emergency

load transfers, maintenance, or other routine switching conditions

where line or feeder load temporarily exceeds the normally

anticipated levels.

TPG ground trip control

The TPG control includes phase and ground-fault protection for

systems where increased sensitivity is required. If a ground-fault

is detected, the control will begin a time-current curve delay

sequence. At the completion of the programmed delay, a signal is

issued to trip the vacuum fault interrupter mechanism.

Since the ground-fault curves are more sensitive than the phase

curves, they can offer a distinct advantage in those special

applications where increased sensitivity and speed in overcurrent

protection are required. As a result, coordination with upstream

devices (i.e., electronic reclosers) can be obtained where TCC

coordination is difficult.

TPG SCADA accessory

VFI switchgear, when ordered with the TPG control, may also be

supplied with an optional SCADA accessory. The SCADA accessory

provides the user with remote functionality, along with Status and

Fault indicators, for each TPG-controlled vacuum fault interrupter

mechanism. For additional information, refer to Service Bulletin

S285-75-1, Tri-Phase, TPG, and TPG with SCADA Electronic Control

Installation and Operation Instructions.

1000

100

0.10

0.010

CURRENT

100000100001000100101

Typical

Response

Curve

Minimum

Response

Time

Minimum Response

Time Accessory

1000

100

0.10

0.010

CURRENT

100000100001000100101

200T

EF-500A Minimum Trip

Tri-Phase VFI

with Instantaneous Trip

Composite:

175A ELSP &

40A Bayonet

167 kVA, 1Ø

Phase-trip

with Instantaneous

Trip feature on.

1000

100

0.10

0.010

CURRENT

100000100001000100101

133-400A GND

133-1200A PH

F-280A GND

F-1140A PH

Tri-Phase "F" Curve

and Recloser 133 Curve.

Technical Data 285-10

Effective April 2014

VFI underground distribution switchgear

www.cooperpower.com

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Wells SW-10T Manuale Utente Pagina 7

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