GE BUS1000 User manual

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GE Power Management
BUS1000
Instructions
InstructionsInstructions
Instructions
GEK 98514B
GEK 98514BGEK 98514B
GEK 98514B
Bus Bar Protection
Bus Bar ProtectionBus Bar Protection
Bus Bar Protection

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TABLE OF CONTENTS
GEK-98514B BUS1000 Busbar Protection i
TABLE OF CONTENTS
TABLE OF CONTENTSTABLE OF CONTENTS
TABLE OF CONTENTS
1. DESCRIPTION 1-1
2. TECHNICAL SPECIFICATIONS 2-1
2.1. MODEL LIST 2-1
2.2. MECHANICAL 2-2
2.3. ELECTRICAL 2-2
2.4. ELECTROMAGNETIC COMPATIBILITY STANDARDS 2-4
3. OPERATION PRINCIPLES 3-1
3.1. BASIC PRINCIPLE 3-1
3.2. DIFFERENTIAL UNIT 3-2
3.2.1. BEHAVIOR WITH INTERNAL FAULTS 3-2
3.2.2. BEHAVIOR WITH EXTERNAL FAULTS 3-4
3.3. SENSITIVITY EQUATION OF THE PERCENT RESTRAINT UNIT 3-5
3.4. DIFFERENTIAL SUPERVISION UNIT 3-6
3.5. ALARM UNIT 3-6
3.6. LINE OVERCURRENT AND BREAKER FAILURE SUPERVISION UNITS 3-6
3.7. TEST BOX 3-7
3.7.1. DESCRIPTION 3-7
3.7.2. OPERATION 3-8
3.7.3. DIFFERENTIAL UNITS TEST:3-8
3.7.4. ALARM UNIT TEST:3-8
4. APPLICATION 4-1
4.1. SELECTION GUIDE 4-2
4.2. CALCULATION OF SETTINGS 4-2
4.2.1. MAIN CURRENT TRANSFORMERS 4-2
4.2.2. INTERMEDIATE AUXILIARY CURRENT TRANSFORMERS 4-2
4.2.3. MEASUREMENT OF KRESTRAINT PERCENTAGE 4-3
4.2.4. MEASUREMENT OF RMAX 4-3
4.2.5. ADJUSTMENT OF THE SUPERVISION DIFFERENTIAL UNIT 4-4
5. HARDWARE DESCRIPTION 5-1
5.1. CABINETS 5-1
5.2. PANEL MOUNTED RACKS 5-2
5.3. MODULES 5-5
5.3.1. PRINTED CIRCUIT BOARDS 5-5
5.3.2. OUTPUT MODULES 5-5
5.3.3. NON-REMOVABLE MODULES 5-6
5.3.4. LATCHING AND AUXILIARY RELAYS 5-6
5.3.5. FRONT SIDE DEVICES 5-6
5.3.6. INTERNAL ADJUSTMENTS 5-8
5.3.7. FACTORY ADJUSTMENTS 5-8
5.3.8. A CCESSORIES 5-9

TABLE OF CONTENTS
ii BUS1000 Busbar Protection GEK-98514B
6. RECEIVING, HANDLING AND STORAGE 6-1
6.1. ACCEPTANCE TESTS AND EQUIPMENT CALIBRATION 6-1
7. ACCEPTANCE TESTS 7-1
7.1. VISUAL INSPECTION 7-1
7.2. ELECTRIC TEST 7-1
7.3. STABILIZATION RESISTORS TEST 7-1
7.4. AUXILIARY CURRENT TRANSFORMERS TEST 7-1
7.5. PREVIOUS CHECK 7-2
7.6. DIFFERENTIAL UNIT CHECK 7-2
7.6.1. BUS A7-2
7.6.2. BUS B7-4
7.7. DIFFERENTIAL TRIPPING OUTPUT CONTACTS TEST 7-6
7.8. BREAKER FAILURE AND 50 UNITS TEST 7-7
7.9. COUPLING DEVICE TEST 7-8
7.9.1. BUS A7-8
7.9.2. BUS B7-8
7.10. SWITCHING DEVICE TEST 7-9
7.11. TEST ELEMENT TEST 7-10
7.11.1. ACANDSWITCHES CIRCUIT 7-10
7.11.2. ONANDOFF PUSH-BUTTONS CHECK 7-10
7.11.3. TEST MEMORY CHECK 7-10
7.12. UNITS CALIBRATION 7-11
7.12.1. MAIN UNITS 7-11
7.12.2. SUPERVISION UNITS 7-11
7.12.3. ALARM UNIT CALIBRATION 7-12
7.12.4. OVERCURRENT UNITS AND BREAKER FAILURE CALIBRATION 7-12
8. FINAL INSTALLATION & COMMISSIONING 8-1
8.1. SETPOINTS OF THE DIFFERENTIAL PROTECTION.8-1
8.2. SETPOINTS OF THE BREAKER FAILURE 8-1
8.3. INSTALLATION 8-1
8.4. PREVIOUS CHECK 8-1
8.5. ARRANGEMENT AND PRELIMINARY LEADS 8-2
8.6. TESTS WITHOUT LOAD 8-2
8.7. TESTS WITH LOAD 8-2
8.8. OPERATION CRITERIA 8-3
9. TESTS AND PERIODICAL MAINTENANCE 9-1
10. FIGURES 10-1
11. DIMENSIONS 11-1
12. SCHEMATICS DOUBLE BUSBAR 13-15

TABLE OF CONTENTS
GEK-98514B BUS1000 Busbar Protection iii
13. SCHEMATICS SINGLE BUSBAR ¡ERROR!MARCADOR NO DEFINIDO.

1. DESCRIPTION
GEK-98514B BUS1000 Busbar Protection 1-1
1.
1.1.
1. DESCRIPTION
DESCRIPTIONDESCRIPTION
DESCRIPTION
The BUS1000 is a high-speed static protection system aimed at detecting phase to phase and to ground
faults in buses at high voltage substations.
The main unit is an overcurrent three phase differential relay with percentage restraint and stabilization
resistors.
The relay is provided with a very sensible overcurrent differential unit which provides an alarm and blocks
the output of any protection trip in case of an accidental disconnection of any of the measuring units’ inputs
during the normal operation of the substation.
As an option, the protection system may include a detection device for breaker failures, associated to the
differential protection and overcurrent units for individual supervision of tripping from each breaker.
The modular feature of the system allows to carry out various configurations adapted to the specific
characteristics of the buses to be protected (multiple or single-bus, breaker and one half, special
dispositions, etc.)
Depending on the complexity of the application, the protection system is housed in one or more 19
inches standard racks or, as an option, in complete cabinets.
The outstanding features of the BUS1000 system are:
•Does not need dedicated secondary
•Signalling and tripping contacts independent of location.
•Redundant measuring circuits for self-checking.
•Measuring "units" for line currents and operation and restraint magnitudes in order to ease the set up and
maintenance.
•An optional testing system to check the operation of the alarm and measuring units in normal operation
conditions.
•Optional overcurrent units for the supervision of the breaker tripping in every position.
•An optional breaker failure detection device. (Several steps logic available)
•Optional lockout relays (86)
The information given hereafter does not intend to cover all the different details or variations of
the described equipment neither does it intend to foresee any event that may arise during its set up,
operation or maintenance.
Should any further information be requested, or in the event of a specific problem that may need
any information other than that provided, refer to GE POWER MANAGEMENT, S.A.

2. TECHNICAL SPECIFICATIONS
GEK-98514B BUS1000 Busbar Protection 2-1
2.
2.2.
2. TECHNICAL SPECIFICATIONS
TECHNICAL SPECIFICATIONSTECHNICAL SPECIFICATIONS
TECHNICAL SPECIFICATIONS
2.1. MODEL LIST
BUS 1 - - - - - - - - - - DESCRIPTION
1 Single busbar
2 Double busbar
3 Split busbar
4 Triple busbar
- - Specify the number of lines + bus coupler
A Without cabinet
D In cabinet (2000mmx800mmx800mm)
1 Without breaker failure
2 With breaker failure
2 With test rack & short-cicuitable resistors
3 Without test rack & short cicuitable
150Hz
260Hz
C Auxiliar
y
volta
g
e: 125 Vcc.
D Auxiliary voltage: 250 Vcc.
E Auxiliary voltage: 220 Vcc.
F Auxiliary voltage: 110 Vcc.
- - Correlative numbers
Because of the great variety of options and configurations in the BUS1000 systems, a complete list of the
models is not included in this document. The specific information corresponding to the customer's model is
provided with the chosen equipment. The most usual types of models as well as the basic system
components are described below:
•SINGLE-BUS SYSTEMS
•DOUBLE BUS WITH COUPLING SYSTEMS
•SPLIT BUS SYSTEMS
•BREAKER AND A HALF SYSTEMS
•DOUBLE BREAKER SYSTEMS
•MAIN BUS SYSTEMS WITH TRANSFERENCE BUS
•SYSTEMS FOR SPECIAL CONFIGURATIONS

2. TECHNICAL SPECIFICATIONS
2-2 BUS1000 Busbar Protection GEK-98514B
Each of the systems may include the following functions:
Basic model....... DIFFERENTIAL PROTECTION
Option 1............. OVERCURRENT TRIPPING SUPERVISION
Option 2............. BREAKER FAILURE (Several steps logic available upon request)
Option 3............. TEST UNIT
System packaging options:
A ........................ Board mounted standard racks
D........................ Complete cabinets
2.2. MECHANICAL
•Mechanical packing in a 19” inch 4 units high stainless steel box.
•IP51 Grade Protection (IP55 housed in a cabinet).
•Rear connection by means of 16 strips of 8 terminals or 16 strips of 12 terminals. Stair layout of
the terminal blocks if mounted in a cabinet.
•Dimensions:
Rack: 484 mm x 179 mm x 349 mm.
Cabinet: 800 mm x 800 mm x 2000 mm (Pedestal: 750x800x100 mm).
•Ambient humidity: up to 95 without condensing.
•Temperature:
Operation: -20º to + 55º C
Storage: -40º to + 65º C
2.3. ELECTRICAL
•Frequency: 50/60Hz
•Auxiliary voltage: 110 Vdc or 125 Vdc or 220 Vdc
•Operation ranges: 80%to 120% of nominal values
•Nominal current:1amp
•Thermal capacity current circuits:
Input circuits:
Continuously................................................... 2 x In
For three seconds ........................................ 50 x In
For one second ...........................................100 x In
Total current going through the bar:
Continuously..................................................20 x In
•Thermal capacity for voltage circuits:
Continuous: ..................................................... 2.5x Vn
During 1min:...................................................... 3.5xVn
•Loads:
Current: 15VA (depending on the tap of the auxiliary transformer used)
Voltage: 0.2 VA at Vn= 63 V

2. TECHNICAL SPECIFICATIONS
GEK-98514B BUS1000 Busbar Protection 2-3
•Requirements for Line Current Transformers
•Relation between the maximum and minimum C.T. ratios in all the positions connected to the
same bus .................................................10 maximum
•Minimum saturation voltage required for main C.T's (for IN = 5 amps) 100 V
•Intermediate Current Transformers: Normal ratios 5/2-1.33-1-0.5-0.2. Other ratios, including
multiple ratios are available according to application.
•Stabilization Resistance: 250 Ohms.
•Restraint Percentage: Adjustable form 0.5 to 0.8 in 0.1 steps
•Sensitivity: (for internal faults): Adjustable form 0.2 to 2.0 amps
•Operation time (output relay included): Below 10 milliseconds
•Alarm Unit:
Operation threshold: 0.027 Amps.
Operation time: 10 Seconds.
•Short-circuit link for coupling currents: operation time adjustable between 100 and 1600
milliseconds.
•Line Trip Supervision Units (optional)
•Independent Units: Operation threshold between 0.2 and 3.3 amps
•Dependent units: Operation threshold between 25 and 100% of the breaker failure unit
adjustment.
•Breaker failure units (optional):
Operation threshold between 0.2 and 3.3 amps
Reset time below 12 milliseconds
Discrimination time between 100 and 730 milliseconds
•Infeed Source: 125 VDC. Amps systems consumption in mA.
Normal Tripped
Single bus system 280 670
Trip output (per position) - 65
Supervision and breaker
Failure units (per position) 70 140
•Trip contacts:
Make and carry for trip cycle (according to ANSI C37.90)........30 amps
Break: Resistive 180 VA at 125/250 VDC.
Break: Inductive 60 VA at 125/250 VDC.
•Accuracy:
Operation current: 5%
Operation time: 5%

2. TECHNICAL SPECIFICATIONS
2-4 BUS1000 Busbar Protection GEK-98514B
2.4. ELECTROMAGNETIC COMPATIBILITY STANDARDS
The BUS1000 units comply with the following standards, including the GE standard for insulation and
electromagnetic compatibility and the standard required by the EU directive 89/336 for the CE marking,
according to the harmonised European standard:
Test Standard Class.
•Insulation IEC 255-5 2 kV 50/60 Hz 1 minute
•Impulse 1.2/50 ms IEC 255-5 5 kV, 0.5 J
•Interference 1 Mhz IEC 255-22-1 2.5 kV common, 1 kV differential
•Electrostatic discharge IEC 255-22-2 Class IV: 8 kV contact, 15 kV air
EN 61000-4-2
•Fast Transient IEC 255-22-4 Class IV: 4 kV
EN 61000-4-4
•Magnetic fields EN 61000-4-8 30 TA/m
•Radiated Emisivity EN 50081-2 Class A
•Immunity RF radiated EN 50082-2 10V/m26-1000Mhz 1kHz AM80%
(Items 1.1 &1.2) 10 V/m 900 Mhz 200 Hz PM 50%
•Immunity RF conducted EN 50082-2 10 V 0.15-80 Mhz 1 kHz AM 80% (Items 2.1,
3.1, 4.1 & 6.1)
•The units comply as well with the following ANSI standards:
C37.90 (Standard for relays and relay systems)
C37.90.1 (Surge withstand capability)
C37.90.2 (Withstand capability to radiated interference)

3. OPERATION PRINCIPLES
GEK-98514B BUS1000 Busbar Protection 3-1
3.
3.3.
3. OPERATION PRINCIPLES
OPERATION PRINCIPLESOPERATION PRINCIPLES
OPERATION PRINCIPLES
3.1. BASIC PRINCIPLE
The measurement method relies on Kirchhoff´s current law.
This law states that the vectorial sum of all currents flowing into a closed area must be zero. This law
applies, in the first instance, to dc current. It applies to ac current for instantaneous values. Thus, the sum of
the currents in all feeders of a busbar must be zero at any instant in time.
I1I2I3.... I
n
Figure 3.1. Busbar with “n” feeders
Assuming that the currents I1,I
2,I3... Inflow in the feeders ( Fig 3.1) connected to the busbar, the following
equation applies in the fault-free condition ( the currents flowing towards the busbar are defined as positive,
and the currents flowing away from the busbar as negative ) :
I1+I
2+I 3... + In=0
If this equation is not fulfilled, then there must be some other-impermissible-path through which a current
flows. This means that there is a fault in the busbar region.
This law is superior, as the basis for busbar protection, to any other known way of measurement. A single
quantity, the sum of currents, characterises and can be used to detect faulty conditions. This sum of all
currents can be formed at any time and if formed as such, using instantaneous current values, full use of
above law can be made. Above law is always valid, whereas with a comparison of only the zero crossing
points of the currents or of the current directions may involve phase displacements that would have to be
considered accordingly. For instance, in a fault-free three-phase load, the instants of zero current are
displaced by 50º or 120º with respect to e. Unbalanced load may produce other displacements. The sum of
the currents, on the other hand, remains constantly zero as long as no currents flow through some other
path due to a fault.
The above considerations apply strictly to the primary conditions in a high-voltage switching station.
Protection systems, however, cannot carry out direct measurements of currents in high-voltage systems.
Protection equipment measurement systems, performing the current comparisons, are connected through
current transformers. The secondary windings provide the currents scaled down according to the
transformation ratio while retaining the same phase relation. Furthermore, the current transformers, due to
the isolation of their secondary circuits from the high-voltage system and by appropriate grounding
measures, can keep dangerous high voltages away from the protection system.
The current transformers are an integral part of the whole protection system and their characteristics are an
important factor for the correct operation of the protection. Their physical locations mark the limits of the
protection zone covered by the protection system.

3. OPERATION PRINCIPLES
3-2 BUS1000 Busbar Protection GEK-98514B
3.2. DIFFERENTIAL UNIT
Figures 1 and 2 represent the simplified connection diagram of the differential protection and its
behaviour with internal and external faults respectively, without any saturation on C.T. cores.
Auxiliary intermediate current transformers are aimed at equalising the currents received by the relay for
every input position, since the main transformers may have a different transformation ratio. They have been
specially designed to provide a homogeneous response (same saturation characteristic) for all the inputs to
the measure unit, thus allowing the use of main transformers with different characteristics.
The VDcurrent is the operation magnitude and it is proportional to the differential current. The VFvoltage
is the restraint magnitude and it is proportional to the sum of the currents of all the positions associated to
the bus to be protected.
In ideal conditions, for an external fault, current flows through the input circuits of the different positions
without differential current; thus, VDis zero and VFis equal to twice the value of the fault current, whereas for
an internal fault, all the fault current goes through the differential circuit which makes VDand VFequal.
Figure 15 shows the block diagram of the percentage restraint differential unit and the supervision
differential unit.
For the main measure unit, VDand VFvoltages are applied to a sum circuit which subtracts from the VD
value part of the VFrestraint voltage value obtaining thus a combined signal which is applied to a level
detector. The restraint current ratio K subtracted from the differential voltage is called restraint percentage
and it determines the operation characteristic of the unit as well as its sensitivity.
The level detector is a fixed VOthreshold level comparator (factory adjusted), with an operation time of
1.5 milliseconds and a reset time of 40 milliseconds in order to ensure a constant signal in the output relay.
The Volevel of the detector is calculated so that the unit may produce an output when the ID-KI
F
magnitude is over 0.1 Rms. Figure 3 shows the operation characteristic corresponding to this equation.
3.2.1. BEHAVIOUR WITH INTERNAL FAULTS
In the case of internal faults, we assume that no current transformer is saturated and therefore the
equivalent circuit with its corresponding current distribution is that of fig.1.
Note that in these conditions all the fault current will pass through the differential unit. From the design of the
circuit we have:
NED =N
EF = N (1) Input transformer's ratio
RD=R
F= R (2) Load resistance of the restraint and differential transformers.
By analysing the behaviour of the differential unit in the first half cycle of the current at a 50 Hz rated
frequency in the network we will have:
V 0
090180
18T
90 -9T
V-KV
DF

3. OPERATION PRINCIPLES
GEK-98514B BUS1000 Busbar Protection 3-3
Where: VD= RMS voltage in the differential circuit.
VF= RMS voltage in the restraint circuit.
VO= Threshold voltage in the level detector.
ID= RMS current in the differential circuit.
IF= RMS current in the restraint circuit.
K= Restraint percent in unit value.
T= Detector time (in ms.).
We will have the following values’ ratio:
On the other hand, the differential unit will produce an output when the VA value is above the VOone, that is,
when:
or what is the same when:
The circuit design values are:
Vo= 0.137 V
T=1.5ms.
N = 0.01
R = 100 ÿ
With these values the equation is reduced to:
For an internal fault ID=I
F
,so:
From this equation we obtain the relay's sensitivity in amperes for the different values of K.
RNIRNIV DDEDDD **** ==
RNIRNIV FFEFFF **** ==
OFD VTVKV ≥−− )990sen(*)*(*2 [5]
[6]
1.0* ≥− FD IKI [7]
)1/(1.0 KID−≥ [8]
)*1(*))990sen(*2/1(** RNTVIKI OFD −≥−

3. OPERATION PRINCIPLES
3-4 BUS1000 Busbar Protection GEK-98514B
3.2.2. BEHAVIOUR WITH EXTERNAL FAULTS
3.2.2.1. Without saturation
During the time prior to the saturation of any of the main C.T's and assuming ideal conditions for an external
fault, the fault current flows through input circuits of the various positions without any differential current.
In these conditions the value of VD= 0 and in our case, the value of VFwill be proportional to twice the fault
current. See fig. 2.
3.2.2.2. With saturation
In the case of an external fault, saturation may be produced in the current transformers associated to any of
the protected bus positions. In this case, the inputs' currents will not be compensated; thus a differential
current will be produced which must not lead to the operation of the relay. The combination of the percent
restraint operation characteristic together with the REstabilization resistance in the differential circuit ensures
the correct behaviour of the unit in these circumstances.
The worst case from the point of view of the possibility of false operations with external faults is that of a
complete saturation (total absence of signal in the secondary) of only one of the main C.T's while the rest
behave correctly.
In our case, the equivalent circuit is shown in fig. 4. Here, the fault current provided by the rest of the current
transformers is divided between the totally saturated IXcircuit and the IDdifferential circuit in an inversely
proportional way to the resistance of every circuit.
Thus, when the REresistance value increases in the differential circuit, the differential current flowing
erroneously in case of saturation of a current transformer decreases. In the same way, when the K restraint
percent value increases, a greater differential current is allowed without providing a trip in the unit since VF
will increase.

3. OPERATION PRINCIPLES
GEK-98514B BUS1000 Busbar Protection 3-5
3.3. SENSITIVITY EQUATION OF THE PERCENT RESTRAINT UNIT
From fig. 4 we may draw out the following equations.
From (1) and (2) we have:
We find that the unit will produce an output (operate) when:
So:
In the same way the unit does not operate when:
For more security we can say that the unit will not trip if:
OR
Thus:
From this we can finally deduce that:
XFAULTD III −=
MAXXED RIRI ** =[10]
[9]
))/(1(*
)/(*
MAXED
MAXEDDFAULT RRI
RRIII += =+=
)/(*))/(1(* MAXEDMAXEDXFAULTF RRIRRIIII ++=+=
))/(*21(* MAXEDF RRII +=
[11]
[13]
[12]
1.0* ≥− FD IKI
))/(*21(** MAXEDD RRIKI +≥
1.0)))/(*21(*1(* ≥+− MAXED RRKI
[14]
[15]
1.0)))/(*21(*1(* <+− MAXED RRKI [16]
0)))/(*21(*1(* <+− MAXED RRKI
0))/(*21(*1 <+− MAXE RRK
))/(*21(*1 MAXE RRK +<
EMAXMAX RKRKR **2* +< [17]
[18]
[19]
KRK
RE
MAX −
<1**2 [20]
KKRR MAXE 2/)1(* −>

3. OPERATION PRINCIPLES
3-6 BUS1000 Busbar Protection GEK-98514B
The REhas a fixed value set at 250 ,sotheR
MAX value must be such that the below equation is
accomplished in order to avoid false operations with external faults, even in the worst saturation conditions
of the main C.T's
3.4. DIFFERENTIAL SUPERVISION UNIT
The supervision differential unit consists of a level detector with similar characteristics to that of the main
unit, to which is applied the VDvoltage only, proportional to the differential current. Its operation threshold is
directly adjustable in Amps from 0.2 A to 2 A and independently from the K adjustment of the main unit (see
block diagram in figure 3).
The combination of both units described provides a great security to the protection, thus guarantying that
any failure of a component will not provide a non-desired trip to all the positions associated to the protected
bus. Both units must operate simultaneously so that a trip output is produced. In the case where due to a
failure only one of the units is operating incorrectly, the alarm unit described below will detect it, thus
providing a signalling output and the blocking of the protection.
3.5. ALARM UNIT
The alarm unit associated to the differential protection consists of a very sensitive overcurrent unit (0.027
amps) connected in series to the differential circuit through its own input transformers.
It is aimed at detecting unbalances in the differential circuit due to leaks or accidental disconnection of any of
the inputs to the measure unit. It is also provided with a circuit that detects discordance among the outputs
of the main measuring units and the outputs of the main measuring and supervision units.
The unit provides a timed output (10 seconds).
Figure 5 shows the block diagram.
3.6. LINE OVERCURRENT AND BREAKER FAILURE SUPERVISION UNITS
These units are optional and may belong to a complete BUS1000 system (current supervision only,
breaker failure only or both).
Figures 6 show the block diagrams of a double bus system with both functions for three-phase trip line
protection and single-phase trip respectively.
The units are connected in series to the inputs of every position of the bus differential (one for each position),
through their own input transducers and signal conditioning. Signals coming from each phase are combined
in a selection circuit of the larger before going on to the level detectors of the trip supervision unit (50) and of
the breaker failure unit (BF).
The breaker failure unit picks up its timer only when an external signal comes from line protection relays. In
the case of lines with single-phase trip protection, the level detector receives only signals from those phases
which have been tripped, in order to avoid the operation of the unit with the load current of the non faulted
phases. (See drawing 226B6429F20,21,22). Signals 89AY and 89BY provide information to the bus to which
the line is connected (double-bus systems), in order to lead the trip to the positions connected to the
corresponding bus.

3. OPERATION PRINCIPLES
GEK-98514B BUS1000 Busbar Protection 3-7
3.7. TEST BOX
As an option, the bus differential protection may be provided with a testing element, whose aim is to
check the differential circuit operation (including the stabilization resistors) and the alarm and differential
units. These includes the following modules:
•DAL: Alarm board (one per bar).
•DDF: Differential boards (one per pole).
•DRD: Differential output module (one per bar).
•DDI: Differential unit input module (one per bar).
This element is provided with elements (latching relays: 3B/87) for the connection and disconnection of the
trip of the differential units (see drawing 22B6429F26).
3.7.1. DESCRIPTION
The test box unit is housed in a 19" rack and consists of the following elements:
•HLB100 (3B/87 in the schemes) latching relay (one for every differential). This relay inhibits the trips of
the corresponding differential units (see drawing 22B6429F26).
•HLA100 (3P/87 in the schemes) auxiliary relays (one for every differential). This relay is in charge of
introducing the test current in the corresponding differential unit (see drawing 22B6429F16).
•DPR test module. This module is provided with the following elements:
•Connection button (green color): This button operates on the HLB100 (3B/87) latching relay
allowing the trip output of the differential units.
•Disconnection button (red color): This button operates on the HLB100 (3B/87) latching relay
•Test button (white color): This button operates on the HLA100 (3P/87) auxiliary relay following
the below sequence:
a) Disconnection of the trips of the differential unit through the HLB100 (3B/87) latching relay (if
connected), while memorising whether it was connected or disconnected. Trips from the
breaker failure logic are not disconnected.
b) It blocks the reset of the HLB100 (3B/87) relay during the whole time the test is being carried
out and until all the elements which make up the trip circuits have been reset.
c) It operates on the HLA100 (3P/87) relay introducing the test current in the differential circuit.
d) When releasing the button, it carries out the opposite operation firstly disconnecting the test
current and connecting secondly (if it were memorised) the trips of the differential units, once
the trip circuits have been completely reset.
•AL, DIF selector switch: It allows for selection between the differential unit test and the alarm
unit test.
•Phase selector switch: It allows for selection of the phase to be tested.
•Current level selector switch: It allows for selection of three different test current levels.

3. OPERATION PRINCIPLES
3-8 BUS1000 Busbar Protection GEK-98514B
3.7.2. OPERATION
The testing element, which may be optionally provided with bus differential protection, has been designed to
check the alarm and differential units, during maintenance.
In the alarm and differential units test it is not necessary to disconnect the protection through its OFF button.
The TEST button itself is, as a step prior to the application of test current, in charge of disconnecting the
trips and not allowing for reset until all the elements in the trip circuits have not been reset.
Bear in mind that while doing the test there will come out the Differential Tripping signalling caused by the
test, and the Blocking signalling. Do not forget to reset the alarm and the differential modules, whose LED
will lit as a probe that each unit has no problem.
3.7.3. DIFFERENTIAL UNITS TEST:
The differential units test will be carried out separately in every phase and with the current level
corresponding to the restraint measured in the protection measuring terminals.
Set the AL - DIF selector to the DIF position and we shall then select the phase to be tested and the level
corresponding to the restraint, with the appropriate switches.
Once the previous adjustments have been carried out, push the TEST button and check that the selected
unit has operated and the unit trip signalling the corresponding LED remains lit.
3.7.4. ALARM UNIT TEST:
The alarm unit test will be carried out separately in every phase. Set the AL - DIF switch to the AL position
and we shall then select the phase to be tested with the phase selector switch. In this case the test current is
fixed and does not depend on the current level selector switch.
Once the previous adjustments have been carried out, push the TEST button and do not release it until the
unit operates (usually 10 seconds). Check that the unit selected has operated and the unit trip signalling
LED remains on.