Basler Electric BE1-87B User Manual

INSTRUCTION MANUA L

ITEM NUMBER: BE1-87B-S5AA1YN0N0F
CURRENT SENSING: 1A/5A, 50/60Hz
POWER SUPPLY: 125/250V AC/DC
SERIAL NUMBER: H0015870 REV A

BE1-87B

Voltage CurrentVoltage

CT OV

40%

20%

30%

60%

Alarm

10%

50%

70%

80%

Reset

Pickup

250

Pickup

200

50

100

150

350

400

300

1.00

.25

2.50

1.75

Tri p

Test

Power

Relay

Bus
Differential

Tri p

D2853-1
12-19-00

®

minute

Test

one

Press

CT

FOR

BUS DIFFERENTIAL REL AY

BE1-87B

Publication: 9282300990
Revision: P 10/14

INTRODUCTION

sensing circuit creates a low

This instruction manual provides information about the operation and installation of the BE1-87B Bus
Differential Relay. To accomplish this, the following information is provided:

• General Information and Specifications

• Controls and Indicators

• Functional Description

• Installation

• Testing

WARNING!

To avoid personal injury or equipment damage, only qualified personnel should
perform the procedures in this manual.

The paddle plugs should be removed prior to performing a current circuit
insulation test. The design of the voltage­resistance path to gro und when the pad dle p lugs ar e insta lled, w hich res ults i n
incorrect test results.

NOTE

Be sure that the BE1-87B is hard-wire d to earth ground with no smaller t han
12 AWG copper wire attac hed to the ground terminal on the rear of the unit
case. When the BE1-87B is configured in a system with other devices, it is
recommended to use a separate lead to the ground bus from each unit.

9282300990 Rev P BE1-87B Introduction i

First Printing: June 1999

WARNING

Basler Electric does not assume any responsibility to compliance or noncompliance with national code,
understood prior to installation, operation, or maintenance.

For terms of service relating to this product and software, see the Commercial Terms of Products and
Services document available at www.basler.com/terms.

This publication contains confidential information of Basler Electric Company, an Illinois corporation. It

procedures, contact Basler Electric for the latest revision of this manual.

The English-language version of this manual serves as the only approved manual version.

Printed in USA

© 2014 Basler Electric, Highland Illinois 62249 USA

All Rights Reserved

October 2014

READ THIS MANUAL. Read this manual before installing, operating, or maintaining the BE1-87B.
Note all warnings, cautions, and notes in this manual as well as on the product. Keep this manual with
the product for reference. Only qualified personnel should install, operate, or service this system.
Failure to follow warning and cautionary labels may result in personal injury or property damage.
Exercise caution at all times.

local code, or any other applicable code. This manual serves as reference material that must be well

is loaned for confidential use, subject to return on request, and with the mutual understanding that it will
not be used in any manner detrimental to the interests of Basler Electric Company and used strictly for
the purpose intended.

It is not the intention of this manual to cover all details and variations in equipment, nor does this
manual provide data for every possible contingency regarding installation or operation. The availability
and design of all features and options are subject to modification without notice. Over time,
improvements and revisions may be made to this publication. Before performing any of the following

BASLER ELECTRIC

12570 STATE ROUTE 143

HIGHLAND IL 62249 USA

http://www.basler.com, [e-mail]

PHONE [phone] FAX [phone]

ii BE1-87B Introduction 9282300990 Rev P

REVISION HISTORY

Revision and Date

Trip Test

General Information,

paragraphs in Section 2,

and added

The following inform ation provides a h istorical summary of th e changes made to this instruction manual
(9282300990) and hardware of the BE1-87B. Revisions are listed in reverse chronological order.

Manual

P, 10/14

O

N, 02/12

M, 01/09

L, 02/07
K, 11/06

J, 07/05

I

H, 06/05

G, 10/03

F, 01/03

Change

• Corrected output contacts specifications in Section 1.

• Added description of hold timer in Section 2.

• Improved Figures 4-1 and 4-8.

• This revision letter not used.

• Moved Input Impedance table from Section 3 to Section 1.

• Simplified note under Table 2-7.

• Standardized case and cover drawings in Section 4.

• Added information about why it is necessary to press the

Pushbutton for up to one minute in Sections 2 and 3.

• Added chassis ground symbol on the ground terminal in Figure 4-10.

• Corrected terminals 15 & 16 numbering in Figures 4-16 and 4-17.

• Added Storage statement in Section 4.

• Minor text edits throug hou t manu al.

• Updated Intentional Delay Jumper instructions on pages 2-11 and 3-5.

• Added option “R” mounting type to Style Number.

• Updated Output Contact ratings in Section 1.

• Added 19” Horizontal Rack-Mount Front and Side views to Section 4,

Installation.

• Added GOST-R certification to Section 1,

Specifications.

• Improved Figure 2-7.

• This revision letter not used.

• Added Two Different Ratio CTs paragraph to Section 2, Application.

• Added information to Internal Faults

Application.

• Improved Figure 2-7.

• Clarified wording of timing specification in Section 1, General

Information, and remove d Figur e 1-3.

• Reworded first paragraph of Sec tion 2, Application, and last paragraph

of Sample Calculation sub-section.

• Removed the polarity mar ks from terminals 15 and 16 of Figures 4-14

and 4-15.

• Information was added to Section 2, Application.

• Moved CT circuit testing information from Section 3, Human-Machine

Interface to Section 5, Testing.

• Moved illustration of Figure 3-3 to Section 4, Installation

terminal designations

• Added metric equivalen ts and mounting depth dimension to F igure 3-4

and moved illustration to Section 4, Installation.

• Corrected various minor errors throughout the manual.

9282300990 Rev P BE1-87B Introduction iii

Manual

Revision and Date

E, 10/01

D, 03/01

C, 04/00

B, 11/99

A, 08/99

—, 06/99

Change

• Corrected the terminal numbering in Figure 2-5.

• Changed the Power Supply Status Contacts label to Relay Trouble

Contacts in Figures 4-13 and 4-14.

• Corrected various minor errors throughout the manual.

• Updated drawings, as required, to reflect changes to the cases and

overlays as a result of “pillow-type” switch implementation for CT Test
pushbutton.

• Updated the style chart with front cover with CT test access option.

• Section 1: Added UL recognition to specifications. Changed voltage

rating specification from “75% of tap setting” to “300 Vac for 1 hour”.

• Section 2: Corrected equation reference under Sample Calculation.

• Section 4: Revised F igures 4-1 and 4-2 to show proper position o f the

Reset button access on the S1 case.

• Changed all power supply status referenc es from “Relay Trouble Alarm”

to “Power Supply Status”.

• Added and updated drawings throughout the manual to accommodate

the three-phase version of the BE1-87B.

• Corrected various errors in the illustrations.

• Initial release

Hardware

Version

T

S
R
Q

P
O
N
M

L

K

J

H
G

F

E

D
C

B

Change

• Improved snubber resistor and SCR protection circuit.

• Updated internal documentation.

• Improved ribbon cable.

• This revision letter not used .

• Improved reset switch on front panel.

• This revision letter not used.

• Improved factory assembly process.

• Improved snubber circuitry to prevent false tripping.

• Internal factory documentation updated.

• Improved power supply board.

• Improved stability of Relay Trouble output contacts during power-

up/power-down.

• Not released to production.

• Corrected labeling for CR1 and CR3 polarity on the SCR circuit board.

• Improved relay stability during cycling of operating power.

• CT Test pushbutton chang ed t o “pi llow -type” switch. Optional cas e cov er

with CT Test pushbutton access introduced.

• Improved immunity to ESD.

• Applied Revision A e nhanc ements to thr ee-phas e re lays with new c ircu it

board design.

• New circuit board design released for single-phase relays.

iv BE1-87B Introduction 9282300990 Rev P

Hardware

Version

A

—

• Enhanced temperature stability and SWC immunity in single-phase

• Initial release

Change

relays.

9282300990 Rev P BE1-87B Introduction v

vi BE1-87B Introduction 9282300990 Rev P

CONTENTS

SECTION 1 • GENERAL INFORMATION ................................................................................................ 1-1

SECTION 2 • APPLICATION .................................................................................................................... 2-1

SECTION 3 • HUMAN-MACHINE INTERFACE ....................................................................................... 3-1

SECTION 4 • INSTALLATION .................................................................................................................. 4-1

SECTION 5 • TESTING ............................................................................................................................ 5-1

9282300990 Rev P BE1-87B Introduction vii

viii BE1-87B Introduction 9282300990 Rev P

SECTION 1 • GENERAL INFORMATION

TABLE OF CONTENTS

SECTION 1 • GENERAL INFORMATION ................................................................................................ 1-1

General .................................................................................................................................................. 1-1

Features ................................................................................................................................................. 1-1

Standard Features .............................................................................................................................. 1-1

Model and Style Number ....................................................................................................................... 1-1

Style Number Example ....................................................................................................................... 1-2

Specifications ......................................................................................................................................... 1-2

Current and Voltage Settings ............................................................................................................. 1-3

Frequency .......................................................................................................................................... 1-3

Pickup Accuracy ................................................................................................................................. 1-3

Output Contacts ................................................................................................................................. 1-3

Current Rating .................................................................................................................................... 1-3

Voltage Rating .................................................................................................................................... 1-3

Targets ............................................................................................................................................... 1-3

Isolation .............................................................................................................................................. 1-3

Surge Withstand Capability (SWC) .................................................................................................... 1-4

Impulse Test ....................................................................................................................................... 1-4

Radio Frequency Interference ............................................................................................................ 1-4

Electrostatic Discharge (ESD) ............................................................................................................ 1-4

UL Recognition ................................................................................................................................... 1-4

GOST-R Certification ......................................................................................................................... 1-4

Environment ....................................................................................................................................... 1-4

Shock.................................................................................................................................................. 1-4

Vibration ............................................................................................................................................. 1-4

Weight ................................................................................................................................................ 1-4

Case Size ........................................................................................................................................... 1-4

Figures

Figure 1-1. BE1-87B Style Chart ............................................................................................................... 1-1

Figure 1-2. Typical Pickup Current Response Time without a Trip Delay................................................. 1-2

Tables

Table 1-1. BE1-87B Power Sup ply Spec i ficat ions .................................................................................... 1-2

Table 1-2. Input Impedance While Triggered and Not Triggered .............................................................. 1-3

9282300990 Rev P BE1-87B Application i

ii BE1-87B Application 9282300990 Rev P

SECTION 1 • GENERAL INFORMATION

General

The BE1-87B is a high-speed, high-impedance, soli d-state differential re lay. It was designed spec ifically
for bus differentia l pro tec ti o n. B ec ause of the relay’s high imp eda nc e, it c an be used in other applica tio ns ,
such as the protection of shunt reactors. Con tact your local Bas ler Applications Eng ineer for information
about additional applications.

Features

The BE1-87B offers high-speed fault protection, wh ich may be applie d to individual ele ments or zones of
ac power systems. It op erates in less than 7 mil liseconds for fault levels of 1.5 times the curren t pickup
and less than 5.5 milliseconds for fault levels above six times the current pickup. This high-speed
operation minimizes pot ential damage to the protect ed equipment. Response c haracteristics for sensin g
input ranges one and two are shown in Section 5, Testing.

Standard Features

Available in single-phase or three-phase models

• S1 and M1 double ended drawout cases and 19” rack-mount

• Percent of pickup voltage alarm

• Differential logic test

• LED trip output indicators

• Power supply status

• Ten position incremental adjust for the voltage and current pickup settings

Model and Style Number

The electrical characteristics and operational features included in a specific relay are defined by a
combination of letters and numbers, which constitutes the device’s style number. The style number
together with the model nu mber describ es the feature s and options in a particu lar device and a ppears on
the front panel as the item number. They also appear in the drawout cradle, and inside the case
assembly. The model number BE1-87B designates the relay as a Basler Electric Class 100, high­impedance bus differential relay. The style chart is shown in Figure 1-1.

Figure 1-1. BE1-87B Style Chart

9282300990 Rev P BE1-87B Application 1-1

Style Number Example

The style number identif ication ch art defines th e electric al character istics and operation feat ures incl uded
in the BE1-87B relay. For ex ample, if the style num ber were BE1-87B S 5AA1YN0N0F, the dev ice would
have the following:

BE1-87B

S.......... Single-phase current sensing

5 .......... 5 ampere current sensing input range

A ......... Front case cover with CT test button access

A1 ....... Instantaneous timing

Y.......... 48/125 Vac/Vdc power supply

N ......... No Option

N ......... No Option

N ......... No Option

0 .......... No Option

F .......... Semi-flush case mounting

Specifications

Timing

A maximum of seven milliseconds at 1.5 times the pickup setting.
A maximum of 5.5 milliseconds above six times the pickup setting.
Figure 1-2 illustrates typical response times.

Figure 1-2. Typical Pickup Current Response Time without a Trip Delay

Power Supply

Power for the internal circuitry may be obtained from either an ac or a dc external power source as
indicated in Table 1-1.

Table 1-1. BE1-87B Power Supply Spec i fications

Type

Y 48/125 Vdc

Z 125/250 Vdc

1-2 BE1-87B Application 9282300990 Rev P

Nominal Input

Voltage

110Vac

110/230Vac

Input Voltage

Range

24 to 150 Vdc
90 to 132 Vac

60 to 250 Vdc
90 to 230 Vac

Burden at Nominal

(Maximum)

7.5 W

15.0 VA

7.5 W

20.0 VA

Current and Voltage Settings

Voltage Alarm Pickup ............................. 10 to 80% in 10% increments

Voltage Pickup ........................................ 50 to 400 V in 50 V increments

Current Pickup ........................................ 0.25 to 2.5 A in 0.25 A increments

Table 1-2 describes input impedance w hile the SCRs are triggered (low impedance) and while the SCRs
are not triggered (high impedance).

Table 1-2. Input Impedance While Triggered and Not Triggered

Impedance State

Low Impedance (SCRs Triggered, Current Circuit Active) 0.05 0.05

High Impedance (SCRs Not Triggered, Voltage Circuit Active)

Input Impedance in Ohms

60 Hz Nominal 50 Hz Nominal

4000 - j3300
5100 ∠ –40°

4500 - j3100
5500 ∠ –35°

Frequency

Nominal 50 or 60 Hz, ± 5 Hz

Pickup Accuracy

±5% of the setting over the operating ranges for both current and voltage. Pickup accuracy over the ±5 Hz
nominal frequency variation is within ±8% of the nominal frequency value.

Output Contacts

Output contacts are rated as follows.
Resistive

120/240 Vac ............................................ Make and carry 30 Adc for 0.2 s , c arr y 7 Adc c ont in uo us ly, br eak

7 Aac

125/250 Vdc ............................................ Make and carry 30 Adc for 0.2 s, c ar ry 7 Adc continuously, break

0.3 Adc

Inductive

120 Vac, 240 Vac, 125 Vdc, 250 Vdc ..... Break 0.1 A (L/R = 0.04)

Current Rating

Continuous .............................................. 10 A rms

1 second, symmetrical ............................ 160 A rms

5 cycles, symmetrical ............................. 480 A rms

2 cycles, fully offset ................................ 215 A

Voltage Rating

The nature of the BE1-87B relay’s application is that voltage is not applied continuously. For calibration
and test purposes, it may be of value to apply input voltage for a longer duration than the few milliseconds
that would typify an internal or external power system fault. For test and calibration purposes, the BE1­87B has been designed to withstand 300 Vac for a maximum duration of 60 minutes.

Targets

LED indication (Trip LED) is latched with an internal, mechanical latching relay. Reset is accomplished by
pressing the Reset button on the front panel.

Isolation

In accordance with IEC 255-5 and IEEE C37.90, one-minute dielectric (high potential) tests were
performed as follows.

All circuits to ground ............................... 2000 Vac or 2828 Vdc

Each circuit to all other circuits ............... 2000 Vac or 2828 Vdc.

9282300990 Rev P BE1-87B Application 1-3

Surge Withstand Capability (SWC)

Oscillatory and Fast Transient ................ Qualified to IEEE C37.90.1-1989

Impulse Test

Qualified to IEC 255-5.

Radio Frequency Interference

Maintains proper operation when tested for interference in accordance with IEEE C37.90.2 1995.

Electrostatic Discharge (ESD)

In accordance with IEEE C37.90.3, contact discharges of 8 kilovolts and air discharges of 15 kilovolts
were applied with no misoperation occurring.

UL Recognition

Recognized per Standard 508, UL File Number E97033.
Note that output contacts are not UL recognized for voltages greater than 250 V.

GOST-R Certification

GOST-R certified per the relevant standards of Gosstandart of Russia.

Environment

Temperature

Operating Range .................................... −40°C to 70°C (−40°F to 158°F)

Storage Range ........................................ −40°C to 85°C (−40°F to 185°F)

Humidity

Qualified to IEC 68-2-38, First Edition 1974

Shock

Qualified to IEC 255-21-2, Class 1.

Vibration

Qualified to IEC 255-21-1, Class 1.

Weight

1-phase Relay ......................................... 14.3 lb (6.5 kg) maximum

3-phase Relay ......................................... 19.2 lb (8.8 kg) maximum

Case Size

1-phase Relay ......................................... S1

3-phase Relay ......................................... M1 or 19” Rack-Mount

Case dimensions are provided in Section 4, Installation.

1-4 BE1-87B Application 9282300990 Rev P

SECTION 2 • APPLICATION

TABLE OF CONTENTS

SECTION 2 • APPLICATION .................................................................................................................... 2-1

Application.............................................................................................................................................. 2-1

Application with Lightning Arr es ters ................................................................................................... 2-1

Application with a Lockout Function ................................................................................................... 2-1

Current Source for High Impedance Differential Relaying ................................................................. 2-1

BE1-87B Flexibility ................................................................................................................................. 2-2

Bus Protection Application ................................................................................................................. 2-2

Shunt Reactor Protection Application ................................................................................................ 2-4

Mixing Two Different Ratio CTs ......................................................................................................... 2-5

General Settings Guidelines .............................................................................................................. 2-5

Operating Principles ............................................................................................................................... 2-5

External Faults ................................................................................................................................... 2-6

Internal Faults ..................................................................................................................................... 2-7

Characteristics ..................................................................................................................................... 2-10

Differential Voltage Pickup ............................................................................................................... 2-10

Differential Pickup Current ............................................................................................................... 2-10

Alarm Voltage Pickup ....................................................................................................................... 2-10

Trip Test Pushbutton ........................................................................................................................ 2-11

CT Test Pushbutton ......................................................................................................................... 2-11

Power LED ....................................................................................................................................... 2-11

Intentional Delay Jumper.................................................................................................................. 2-11

Operating Times ............................................................................................................................... 2-11

Calculation of Settings ......................................................................................................................... 2-12

Calculation of Voltage Differentia l Sett in gs ...................................................................................... 2-12

Bus Protection .................................................................................................................................. 2-13

Shunt Reactor Protection ................................................................................................................. 2-13

Application with Mixed Multi-Ratio CTs ............................................................................................ 2-13

Current Element Setting ................................................................................................................... 2-14

Minimum Fault to Trip (Voltage Element) ......................................................................................... 2-14

Sample Calculation .............................................................................................................................. 2-15

CT Test Circuit Calculations ................................................................................................................ 2-16

General ............................................................................................................................................. 2-16

Definition of Terms ........................................................................................................................... 2-16

Calculation Steps ............................................................................................................................. 2-17

Example Calculation ......................................................................................................................... 2-17

Figures

Figure 2-1. External AC Connections for Bus Protec t io n .......................................................................... 2-3

Figure 2-2. External DC Connections for Bus Prot ection .......................................................................... 2-4

Figure 2-3. External AC Connections for Shunt Reactor Protection, Multi-Phase and Line-to-Ground

Faults ......................................................................................................................................................... 2-4

Figure 2-4. External AC Connections for Shunt Reactor Protection, Ground Faults ................................ 2-5

Figure 2-5. Illustration of Single Line-to-Ground Fault at Location F1 ...................................................... 2-7

Figure 2-6. Typical Secondary Excitation for 1200/5 Bushing Current Transformer ................................. 2-8

Figure 2-7. Simplified Internal Connection Diagram for BE1-87B Relay ................................................... 2-9

Figure 2-8. Voltage Appearing Acros s Ful l Windi ng of CT ...................................................................... 2-10

Figure 2-9. Voltage Appearing Acros s Ful l Windi ng of CT ...................................................................... 2-17

Figure 2-10. Voltage Appearing Acr os s Full Wind ing of CT .................................................................... 2-18

9282300990 Rev P BE1-87B Application i

ii BE1-87B Application 9282300990 Rev P

SECTION 2 • APPLICATION

CAUTION

CAUTION

Application

The BE1-87B solid-state, high-speed, high-impedance differential relay is available in single or three­phase models. The relay was specifically des igned to provide high-s peed differential protection for high
voltage buses, critical medium, and low voltage buses. Because of its design and sensitivity, the relay can
also be used for shunt reactor protection. While bus schemes require three-phase protection, shunt
reactors may be protected with only one single-ph ase relay for ground faults . Regardless of the scheme
employed or the equipment protected, the following applications apply to the BE1-87B relay.

Application with Lightning Arresters

The BE1-87B is a hig h-speed relay des igned to operate in a half-cycle or less . As a result, apply ing the
relay to a bus wit h lightning arresters must b e addressed. The relay pick up current range is adjustab le
between 0.25 to 2.5 amper es rms. If lightning ar resters will b e connected to the bus, use the 2.5 amper e
sensitivity setting so as to prevent the possibility of a differential operation during a normal arrester
operation. If no light ning arres ters ar e use d, start with t he 0. 5 amp ere sens itivi ty setti ng and adjus t as the
application dictates.

If lightning arresters ar e added to an exis ting bus, as might be the case w hen
adding a transformer, be sure to increase the Pickup Current setting of the
BE1-87B to the 2.5 ampere setting.

Application with a Lockout Function

Contacts from the lockout relay (86) should be connected across terminals 5 and 6 (single-phase or
phase A for 3-phase models), 3 an d 4 (phase B), and 1 an d 2 (phase C) of the BE1-87B relay to shor t­circuit the SCRs in the inpu t circuit after a trip ou tput has been initiated. This al lows the relay to con tinue
operation as a conventiona l overcurrent relay and at t he same time protect agains t exceeding the short­time rating of the internal SCRs. The relay can be used in any application where the total secondary
current is not more tha n the current waveform of a fully-offset f ault with 215 amperes rms symmetric al
available, provided the lockout relay (86) has an operate time of 1 cycle or less (16 milliseconds).

If the BE1-87B relay co ntrol power (power supply voltage) is removed, relay
terminals 5 and 7 (single-phase model) or 5 and 7, 3 and 7, and 1 and 7
(three-phase model) should be short ed by pull ing the connect ion pl ug. If th is is
not done, the BE1-87B relay c ould b e da mag ed d ue t o c ontin uous f aul t c urr ent
flowing through the relay SCRs.

Current Source for High Impedance Differential Relaying

Predictable current trans former (CT) performanc e is critic al to the eff ective oper ation of a high impeda nce
differential scheme. Where prac tical, t he following current tr ansformer guide lines s hould be appl ied when
using the BE1-87B relay.

• All CTs should be of toroidal design and be fully distributed around the core.

• All CTs should have the same full ratio value and be connected to the full ratio taps.

• All CTs should have the same voltage rating, accuracy class, and thermal rating.

• The CTs should be dedicated to the differential application.

• When adding to an existi ng differenti al scheme, a t lea st one set of CTs in the ne w breaker shou ld be

ordered with the same ratio and accuracy class as the differential CTs used in the existing scheme.

• CTs cannot have pr imary or secondary voltage limiti ng devices, as the resulting shor t-circuit could

cause an unwanted operation of the differential.

9282300990 Rev P BE1-87B Application 2-1

BE1-87B Flexibility

Because of the flexible wid e range design of the BE1-87B, it is possible to ap ply the relay in situations
where the current sensin g input circuit is less tha n ideal. It should be noted, however, that th e possibility
of less sensitive settings, equipment overvoltage, or false operation could resu lt. Careful review of the
following application notes is recommended:

• It is possible to use a m ixtu re of mult i-ratio CTs , howe ver, it is essent ial th at the tapped value h as the

same turns ratio as the other para llel CTs in the circuit. When ta ps are selec ted other than f ull ratio,
use the highest available ta p s etting th at w ill a llow all CT s in the sc heme to hav e t he s ame turns r atio .
Tap settings other than full ratio re quire a calculation of the peak vo ltage developed across the full
winding resulting fro m autotransfor mer action. Th e resulting v oltage shou ld not ex ceed the insula tion
breakdown values of the connected equipment. The equation for this calculation is derived in the
paragraph on operating pr inciples in this section and repeated in the paragraphs on Calculation of
Settings.

• All CTs used in the differential circuit should have negligible leakage reactance on the connected

taps. Most, if not all, multi-ratio internal, bushing, and column type CTs made in the last 30 years
meet this requirement. All CTs wound on toroidally shaped cores meet this requirement if the
windings (on the tap used) are com pletely dis tributed around th e core (co nsult y our CT manufacturer
if you have questions). It m ay be pos sible to us e CTs t hat do not me et th is requir ement if the leak age
reactance is known. T he leakage reac tance is added algebraically to t he resistanc e of the CT circui t
in question. Less sensitive protection will occur as a result of a higher pickup setting.

• It may be possible, although not recommended, to use the differential circuit CTs jointly for other

functions as long as an accur ate impedance of the other functi on is known. The performance of the
system under these c onditions can be ca lculated by alge braically adding th e other impedanc e to the
CT winding and cab le resistance. Less sens itive protection will occ ur as a result of a hi gher pickup
setting. Also, considerat ion must be given to the haz ards of false operatio n due to extra connections
and errors in test ing the added devices . To ensure pr oper relay setting, all cable and CT sec ondary
winding resistances should be ev aluated before a decision is made to a dd other devices to th e BE1­87B CT circuits.

Bus Protection Application

Three single-phase BE1-87 B r elays or one t hree-phase BE1-87B relay and an aux iliar y loc kout relay (86) ,
provide a complete m ulti-p hase and gr ound bus fault protection package. Typical external c onnect ions to
the relays are shown in Figures 2-1 and 2-2. The connections are illustrat ed for a bus w ith three circ uits,
but the protection can easil y be ex tended if more c ircu its are adde d to the bus . For addit ional circ uits, it is
only necessary to connect the CTs associated with the added circuits to the respective junction points and
to connect the contac ts of the lock out relay in the r espective trip c ircuits. The rel ay voltage tap s etting is
based on the maximum voltage that can be developed across the differential junction point during an
external fault. Calc ulation of the max imum voltage is easily made an d methods fo r doing so are giv en in
the paragraph under calculation of settings. A sample calculation for a bus differential scheme is also
provided.

2-2 BE1-87B Application 9282300990 Rev P

TO SURGE

GROUND

52-1

52-3

52-2

3 2 1

3
2
1

3
2
1

TO SURGE

GROUND

Single Phase

87B- 1

RELAY HOUSE

GROUND

TO SURGE

GROUND

D2853-3

5-26-99

86

567

86

5

6

7

86

5

6

7

Single Phase

87B- 2

Single Phase

87B- 3

86

86

86

Three Phase

87B Relay

1

23

4

5

6

7

N

1 2 3

Surge

Ground

Figure 2-1. External AC Connections for Bus Pr otection

9282300990 Rev P BE1-87B Application 2-3

86 86 86

BLOCK AUTOMATIC

RECLOSING

86

87

86

87

52-1

52-252-1

52-3

52-2

52-3

86 86 86

a

aa

TC

TC

TC

(+)

(-)

D2853-4

5-24-99

87 - BE1-87B BUS DIFFERENTIAL RELAY
86 - LOCKOUT RELAY

15

16

17

18

TRIP 1

OUTPUT

TRIP 2

OUTPUT

19

20

87

13

14

VDIFF

ALARM

11

12

RELAY

TROUBLE

TO 2 AND 3

SINGLE PHASE RELAYS

TO 2 AND 3

SINGLE PHASE RELAYS

BE1 - 87B

86

BE1 - 87B

86

BE1 - 87B

86

1

2

3

01

0203

86 - LOCKOUT RELAY

* TO SURGE GROUND

*

*

*

1
2
3

D2853-5

5-25-99

5

6

7

5

6

7

5

6

7

86

86

86

Three Phase

87B Relay

1

23

4

5

6

7

N

1 2 3

*

Figure 2-2. External DC Connecti ons for Bus Protec t io n

Shunt Reactor Protection Application

Differential protection of s hunt reactors may be pr ovided by using only one sin gle-phase BE1-87B relay ,
three single-phase relays, or one three-phase relay. Typical ac external connec tion diagrams for these
schemes are shown in Figures 2-3 and 2-4. The dc connections will be similar to those show n in Fig ure 2-

2. Only ground fault protection will be provided when one relay is applied. Application of either three-

phase arrangement wi ll provide both multi-phase an d phase-to-gro und fault prote ction. Calcu lation of the
voltage tap setting is basically the same as for the bus app lication. The procedures for calculating the
voltage tap setting for either scheme are provided under Calculation of Settings.

2-4 BE1-87B Application 9282300990 Rev P

Figure 2-3. External AC Connections for Shunt Reactor Protection,

Multi-Phase and Line-to-Ground Faults

BE1 - 87B

5

6

7

86

TO SURGE

GROUND

1
2

3

1

2

3

86 - LOCKOUT RELAY

D2853-6

5/25/99

Figure 2-4. External AC Connections for Shunt Reactor Protection, Ground Faults

Mixing Two Different Ratio CTs

While high impedance bus protec tion is bes t conf igure d with all CT s hav ing a co mmon rat io, it is p ossibl e
to utilize two different ratio CTs within one bus protection zone. The process by which this is
accomplished is detailed in the paper “Bus Protective Relaying, Methods and Application” located at

www.basler.com

.

General Settings Guidelines

To obtain the max imum set ting sens itivity, the CT loop res istance shou ld be minimized s o that the low est
possible voltage setting can be selected. For switchyard applications where there is a large distance
between the breaker and the relay panel, it may be desirable to locate the differential junction in the
switchyard since the resistance of the fault CT loop may otherwise be too large. To minimize the
impedance from the current transformers to the junction point, all the secondary windings should be
paralleled in the swi tchyard and as clos e as possible to the c urrent transformer s. Optimally, the junction
point should be equidistant from all current transformers.

The cable resistance fr om the junction point to the re lay is not included as a
part of the fault CT l oop r esistanc e. It is perm issibl e to locate junctio n poi nts at
the panel, providing that the relay setting gives the desired sensitivity.

NOTE

Operating Principles

The BE1-87B high impedance, differential relay operates on the instantaneous value of CT secondary
voltage to which the relay is connected. All the CTs in the differ ential circuit must have the same tur ns
ratio. If all CTs hav e the same turns ratio, the volta ge developed acros s the relay duri ng normal system
conditions is very small. Th e diagram in Figure 2-1 illus trates typical external ac connections to the relay
for use in a bus differential sc heme. As shown in the diagram, a typical differential connec tion is used
consisting of the CT circuits from each bus device connected in wye and paralleled at one location

9282300990 Rev P BE1-87B Application 2-5

(summing point) on a per-phase basis. Three single-phase BE1-87B relays or one three-phase relay

)2R(R )(I 22 Vpeak

LSF

+=

)2R(R IV

LSFR

+=

provide complete protection of the bus. The relay will generate a trip output when the instantaneous
voltage applied across 5 and 7, or 3 and 7, or 1 and 7 o f the thr ee-phase model (A, B, and C res pec tive ly ),
exceeds the voltage pickup setting (V

) and the fault current is greater than the current sensitivity

DIFF

setting.

External Faults

If the differential protection scheme is to perform satisfac torily, then it must not trip for faults external to
the zone of protection . For example, Figure 2-5 shows a on e-line diagram for a three input diff erential
scheme. The BE1-87 B must not operat e for a fault at F1. Since the CT s in the faulted f eeder (CT 3) will
see the most current , assume they will saturate completely, thus causing t he magnetizing reactance to
drop to zero. The total current fr om the other CTs (CT 1 and 2) is for ced through the par allel comb ination
of the high impedance relay (5,000 Ω) and the saturated CT secondary. The saturated CT secondary
winding resistance is i n series with any resistance of the CT leads and connection cables (the total of
which presents a much lower resistance than the 5,000 Ω).

Therefore, nearly all the secondary fault current will flow through the saturated CT. A voltage drop V
caused by the flow of the fault curr ent in this parallel path will a ppear across the BE1-87B relay. For this
fault, the highest volta ge th at coul d be dev elop ed at th e relay w ould oc cur when t he assoc iated CT (CT 3)
saturates completely, an d the others ( CT1 and CT2) did not sat urate at all. When a CT with a distributed
toroidal winding (on t he tap used) saturates complet ely, it produces no voltage and the impedance, as
seen at the secondary w inding, is ver y nearly equal to the winding resistance ( very small impedance).
Thus the highest peak voltage that can be developed across the relay during an external fault will be
equal to the voltage produced by the total secondary fault current flowing through the control cable
resistance plus the wi nding res istance of the CT asso ciated wit h the faulte d feed er. Refer to th e exampl e
case in Figure 2-5 while applying Equation (1):

R

(EQUATIO N 1)

I

= rms symmetrical value of fault current in the fault CT in secondary amps.

F

R

= CT secondary winding resistance plus any lead resistance (at highest expected operating

S

temperature)

= Cable resistance from junction point to CT (at highest expected operating temperature)

R

L

Equation (1) above yi elds the p eak volt age develop ed at the r elay for a complet ely offset wav e of curr ent
having an rms symmetrical value of I

secondar y amperes. Because the BE1-87B relay is cal ibrated in

F

symmetrical rms volts, Equation (2) below, whic h yields the r ms voltage v alue, is us ed in the paragra phs
on Calculation of Settings.

(EQUATION 2)

The pickup voltage of the B E1-87B mus t be set abov e this valu e of rms volt age and above t he rms value
of the other voltages o btain ed in a si milar m anner on a ll the cir cuits of the b us. B ec ause the peak vo ltage
is proportional to the fault c urrent, the highest pos sible v alue of expected f ault cur rent in rms sy mmetrical
amperes should be used in making the evaluation.

2-6 BE1-87B Application 9282300990 Rev P