Substation
Transformers
Electrical Apparatus R210-90-8
Design Options for Substation
Transformer Protection and Isolation
GENERAL
Select a Load Break and Over
Current Protection Method / Control
Mechanism suitable to the features
and functions desired.
Load Break
Mechanism
Mechanical Source Isolation provides
same functionality as a remote visible
break switch. For the Load Break
Switch with Bay-O-Net / ELSP Fuses
combination, Visible Break is realized
by removing the BON fuses after the
Load Break Switch is moved to “Open”
position.
Overcurrent Protection
Method/Control Mechanism
Mechanical Source
Isolation
iXP-420 Protection Relay
Device No. 87, 24, 27/59, 50/51, 81 and more
Intelligence/Sophistication
iDP-210 Protection Relay
Device No. 50/51, 25, 27/59, 32, 67, 81 and more
Vacuum Fault
Interrupter
12-16kA
Symmetrical,
up to 50kA
Symmmetrical
with ELSP fuses
Tri-Phase with Ground Controller and
SCADA Interface Board
Visible Break
(Optional)
Tri-Phase with Ground Controller
Standard offering with VFI mechanism
Tri-Phase Controller
Load Break
Switch—
Loop Feed
Bay-O-Net Fusing or Overcurrent
Relay Monitoring
Load Break
Switch—
Radial Feed
Bay-O-Net / ELSP Fuses
Load Interrupter
Switch
Load Interrupter Fusible Air Switch
March 2010 • New Issue
Dependent upon
type of
Overcurrent
Protection
Visible Break
(Standard)
1
Design Options for Substation Transformer Protection and Isolation
LIS
The Load Interrupter Switch’s quickmake, quick-break mechanism
provides full-load current interrupting
capability while fuses provide accurate,
permanently calibrated short circuit
detecting and interrupting capabilities.
Visibility of actual blade position
improves safety by giving positive
assurance of circuit de-energization.
Only phase(s) that have current
exceeding fuse ampere rating will be
opened prior to switch being tripped.
Figure 1.
LIS Interior view showing power fuses.
LBS with Bay-O-Net/ELSP Fuses
The Load Break Switch allows the
transformer to be switched off so that
the secondary of the unit is safe to be
serviced (after BON fuses are removed)
and allows the loop feed (if equipped)
to remain intact while the secondary
is serviced. A popular combination of
Bay-O-Net expulsion fuses in series
with ELSP back-up current-limiting
fuses, allows the expulsion fuse to
clear in the case of significant overload
or a fault that takes place downstream
of the transformer, while the currentlimiting fuse operates to limit the
energy that feeds a fault within the
transformer tank. Only phase(s) that
have current exceeding fuse ampere
rating will have been opened prior
to switch being moved to “OPEN”
position
Load Break Switch - Loop Feed
Various options for Loop Feed
switching are available including
“Break-Before-Make” and “MakeBefore-Break” functionalities. One
option is shown on the switch position
nameplate. (Figure 5)
A Load Break Switch with Loop
Feed capability can be provided
in combination with Bay-O-Net /
ELSP fusing, or with a Vacuum Fault
Interrupter (VFI) that has one of the
overcurrent relay monitoring options
described on the next two pages.
Figure 3.
Bay-O-Net fuse holders.
Figure 5.
Four position loadbreak switch
Figure 2.
LIS Switch position viewing window.
iXP-420
iXP-420
iXP-420
iDP-210
iDP-210
iDP-210
VFI
TPG
VBS
TPG
VFI
VBS
TPG
VFI
Scada
Scada
Scada
Tri-Phase
Tri-Phase
Tri-Phase
LBS-LF
Fuse/OCR
LBS-RF
BON/ELSP
LIS
2
Figure 4.
LBS Switch handle.
VB
(Std)
LBS-LF
Fuse/OCR
LBS-RF
BON/ELSP
LIS
VB
(Std)
LBS-LF
Fuse/OCR
LBS-RF
BON/ELSP
LIS
VBS
VB
(Std)
R210-90-8
Vacuum Fault Interrupter (VFI)
The Vacuum Fault Interrupter from
Cooper Power Systems provides
resettable overcurrent protection
through the use of proven, reliable
vacuum bottle interrupters. The VFI
mechanism allows immediate service
restoration, eliminating the added
expense & down-time associated with
stocking & replacing conventional
fuses. Being a three-phase device,
the VFI prevents single phasing of
sensitive loads. The VFI also serves as
a load-break switch through a simple
push-pull of its operating handle. For
applications that require remote Trip &
Close functionality, a motor operating
accessory can be provided.
Visible Break Switch (VBS)
The Visible Break Switch from Cooper
Power Systems (an additional feature
available with the Vacuum Fault
Interrupter) aids in source isolation
verification when distribution switching
procedures require indication of
an open circuit prior to testing and
verification. The Visible Break feature
enables an operator to peer through a
sealed viewing window to verify switch
blade position. Large, easily viewed
contacts show the open/close position
of the Visible-Break Switch.
Tri-Phase Control (Optional)
The Tri-Phase electronic controller
allows for ease of time-current curve
coordination and makes use of
internally mounted current transformers
to monitor line current on each phase.
With the use of various TCC curves
and easily selectable amps pickup
value with optional instantaneous trip
selectable setting, system protection
coordination is improved. Through
its intelligence, all three phases are
tripped upon sensing a fault condition.
Figure 8.
Visible Break Switch movable blades
shown in the “open” position.
Figure 6.
VFI - Inside transformer tank
Figure 9.
TPG control with SCADA shown.
Figure 7.
VFI Operating Handle
iXP-420
iXP-420
iXP-420
iDP-210
iDP-210
iDP-210
TPG
VFI
VBS
TPG
VFI
VBS
TPG
VFI
Scada
Scada
Scada
Tri-Phase
Tri-Phase
Tri-Phase
LBS-LF
Fuse/OCR
LBS-RF
BON/ELSP
LIS
VB
(Std)
LBS-LF
Fuse/OCR
LBS-RF
BON/ELSP
LIS
VB
(Std)
LBS-LF
Fuse/OCR
LBS-RF
BON/ELSP
LIS
VBS
VB
(Std)
3
Tri-Phase Control with Ground (TPG)
(Standard with VFI)
Tri-Phase with Ground Trip technology
incorporates a separate zero sequence
circuit and settings for ground fault and
phase loading imbalance detection.
Since these settings are more sensitive
than the phase curves, they can offer
a distinct advantage in those special
applications where increased sensitivity
and speed in detecting phase loading
imbalance conditions are required.
All other features of the standard
Tri-Phase Control are included, plus
option for SCADA accessory as
described below.
SCADA
The discrete Supervisory Control and
Data Acquisition option combines
with the TPG technology to provide
the user with remote trip capability,
along with VFI Status and Faulted
Phase(s) indicators. With interface by
User to their RTU/communications
device, remote trip and VFI status
reporting is available. Incorporating the
remote trip feature allows for tripping
from transformer accessories such
as over temperature, over pressure,
internal fault, etc. In addition, Inrush
Restraint and Minimum Trip Multiplier
accessories are also provided.
iXP-420
iDP-210
TPG
VFI
VBS
Scada
Multifunction Programmable Relays
iDP-210 - In place of the standard
Tri-Phase control, the iDP-210
multifunction programmable relay
can be supplied to provide greater
protection and relaying capability. The
iDP-210 is a full featured relay with
Device No. 50/51 & multiple other
ANSI Device No. functions. Phase
Currents & Event Recorder data and
trip signal to LV Circuit Breaker (by
others) is available on this relay.
iXP-420 - The iXP-420 multi-function
programmable relay can supply all
the protection of the iDP-210 relay
in addition to ANSI Device No. 87
(Differential two-winding transformer
protection). A trip signal from this relay
would command the VFI to trip open
in addition to commanding the LV
Circuit Breaker (by others) to also trip.
Transformer is electrically isolated from
being reenergized at both HV & LV
connections.
If Voltage Transformers are also
included with the Substation
Transformer, then the iDP-210 &
iXP-420 relays can provide metering
functionality at the relay.
The iDP-210 and iXP-420 relays
both have the following additional
capabilities:
1. Data logging
2. Demand metering
3. Direct connection to remote
SCADA communications
4. MODBUS & DNP communication
protocols
5. Built-in harmonic recording &
logging
6. Downloadable sequence of
events record in non-volatile
memory
7. Oscillographic & phasor displays
when connected to laptop with
ProView software
Figure 10.
iDP/iXP Relays without and with Trip/
Close push buttons.
iXP-420
iDP-210
Fuse/OCR
LBS-RF
BON/ELSP
LIS
Tri-Phase
VB
(Std)
Cooper Power Systems and ProView are valuable trademarks of Cooper Industries
in the U.S. and other countries. You are not permitted to use the Cooper
Trademarks without the prior written consent of Cooper Industries.
©2010 Cooper Industries. All Rights Reserved
4
VBS
Scada
Tri-Phase
LBS-LF
TPG
VFI
LBS-LF
Fuse/OCR
LBS-RF
BON/ELSP
LIS
2300 Badger Drive.
Waukesha WI 53188
www.cooperpower.com
VB
(Std)