Alstom MBCH Manuel utilisateur
Service Manual
Type MBCH
Biased Differential Relay
HANDLING OF ELECTRONIC EQUIPMENT
A person's normal movements can easily generate electrostatic potentials of several thousand volts.
Discharge of these voltages into semiconductor devices when handling electronic circuits can cause
serious damage, which often may not be immediately apparent but the reliability of the circuit will have
been reduced.
The electronic circuits of ALSTOM T&D Protection & Control Ltd products are immune to the relevant levels
of electrostatic discharge when housed in their cases. Do not expose them to the risk of damage by
withdrawing modules unnecessarily.
Each module incorporates the highest practicable protection for its semiconductor devices. However, if it
becomes necessary to withdraw a module, the following precautions should be taken to preserve the high
reliability and long life for which the equipment has been designed and manufactured.
1. Before removing a module, ensure that you are at the same electrostatic potential as the equipment
by touching the case.
2. Handle the module by its front-plate, frame, or edges of the printed circuit board.
Avoid touching the electronic components, printed circuit track or connectors.
3. Do not pass the module to any person without first ensuring that you are both at the same
electrostatic potential. Shaking hands achieves equipotential.
4. Place the module on an antistatic surface, or on a conducting surface which is at the same
potential as yourself.
5. Store or transport the module in a conductive bag.
More information on safe working procedures for all electronic equipment can be found in BS5783 and
IEC 60147-0F.
If you are making measurements on the internal electronic circuitry of an equipment in service, it is
preferable that you are earthed to the case with a conductive wrist strap.
Wrist straps should have a resistance to ground between 500k – 10M ohms. If a wrist strap is not
available, you should maintain regular contact with the case to prevent the build up of static.
Instrumentation which may be used for making measurements should be earthed to the case whenever
possible.
ALSTOM T&D Protection & Control Ltd strongly recommends that detailed investigations on the electronic
circuitry, or modification work, should be carried out in a Special Handling Area such as described in
BS5783 or IEC 60147-0F.
Service Manual
Type MBCH
Biased Differential Relay
4
CONTENTS
SAFETY SECTION 7
1 DESCRIPTION 11
2 INSTALLATION 11
2.1 General 11
2.2 Unpacking 12
2.3 Storage 12
2.4 Site 12
3 COMMISSIONING 12
3.1 Commissioning preliminaries 12
3.2 Commissioning tests 13
4 APPLICATION NOTES 17
4.1 General 17
4.2 Matched line current transformers 17
4.3 Ratio and phase matching interposing transformers 18
4.4 Application of matching transformer 19
5 SETTINGS 23
DIAGRAMS
Flowchart 1 24
Flowchart 2 25
Flowchart 3 26
Flowchart 4 27
Flowchart 5 28
Flowchart 6 29
Figure 1 Connections for checking relay settings 30
Figure 2 Connections for checking relay operating time 30
Figure 3 Connections for checking the bias curve 31
Figure 4 MBCH 12/13/16 bias curve 32
Figure 5 Connections to the relay to simulate magnetizing inrush current
waveform 33
Figure 6 Mesh busbar arrangement requiring three bias inputs to the
differential relay 34
Figure 7 Three winding transformer – one power source 35
Figure 8 Switchgear arrangement where six bias inputs may be required 36
Figure 9 Example of a 30 MVA transformer with current flow indicated 37
Figure 10 Disposition of windings on matching transformer 38
Figure 11 Two winding transformer with unmatched line current transformers 39
5
Figure 12 Three winding transformer showing interposing CTs 40
Figure 13 Block diagram: biased differential protection relay Type MBCH12
with two biased inputs 41
Figure 14 Block diagram: biased differential protection relay Type MBCH13
with three biased inputs 42
Figure 15 Block diagram: biased differential protection relay Type MBCH16
with six biased inputs 43
Figure 16 Connection for six change-over tripping contacts for three phase
tripping of up to six circuit breakers 44
6 COMMISSIONING TEST RECORD 45
REPAIR FORM 47
6
7
SAFETY SECTION
This Safety Section should be read before commencing any work on
the equipment.
Health and safety
The information in the Safety Section of the product documentation is intended to
ensure that products are properly installed and handled in order to maintain them in
a safe condition. It is assumed that everyone who will be associated with the
equipment will be familiar with the contents of the Safety Section.
Explanation of symbols and labels
The meaning of symbols and labels which may be used on the equipment or in the
product documentation, is given below.
Caution: refer to product documentation Caution: risk of electric shock
Protective/safety *earth terminal
Functional *earth terminal.
Note: this symbol may also be used for a protective/
safety earth terminal if that terminal is part of a
terminal block or sub-assembly eg. power supply.
*Note: The term earth used throughout the product documentation is the direct
equivalent of the North American term ground.
Installing, Commissioning and Servicing
Equipment connections
Personnel undertaking installation, commissioning or servicing work on this
equipment should be aware of the correct working procedures to ensure safety.
The product documentation should be consulted before installing, commissioning or
servicing the equipment.
Terminals exposed during installation, commissioning and maintenance may present
a hazardous voltage unless the equipment is electrically isolated.
If there is unlocked access to the rear of the equipment, care should be taken by all
personnel to avoid electric shock or energy hazards.
Voltage and current connections should be made using insulated crimp terminations
to ensure that terminal block insulation requirements are maintained for safety.
To ensure that wires are correctly terminated, the correct crimp terminal and tool for
the wire size should be used.
8
Before energising the equipment it must be earthed using the protective earth
terminal, or the appropriate termination of the supply plug in the case of plug
connected equipment. Omitting or disconnecting the equipment earth may cause a
safety hazard.
The recommended minimum earth wire size is 2.5 mm2, unless otherwise stated in
the technical data section of the product documentation.
Before energising the equipment, the following should be checked:
Voltage rating and polarity;
CT circuit rating and integrity of connections;
Protective fuse rating;
Integrity of earth connection (
where applicable
)
Equipment operating conditions
The equipment should be operated within the specified electrical and environmental
limits.
Current transformer circuits
Do not open the secondary circuit of a live CT since the high voltage produced
may be lethal to personnel and could damage insulation.
External resistors
Where external resistors are fitted to relays, these may present a risk of electric shock
or burns, if touched.
Battery replacement
Where internal batteries are fitted they should be replaced with the recommended
type and be installed with the correct polarity, to avoid possible damage to the
equipment.
Insulation and dielectric strength testing
Insulation testing may leave capacitors charged up to a hazardous voltage. At the
end of each part of the test, the voltage should be gradually reduced to zero, to
discharge capacitors, before the test leads are disconnected.
Insertion of modules and pcb cards
These must not be inserted into or withdrawn from equipment whilst it is energised,
since this may result in damage.
Fibre optic communication
Where fibre optic communication devices are fitted, these should not be viewed
directly. Optical power meters should be used to determine the operation or signal
level of the device.
9
Older Products
Electrical adjustments
Equipments which require direct physical adjustments to their operating mechanism to
change current or voltage settings, should have the electrical power removed before
making the change, to avoid any risk of electric shock.
Mechanical adjustments
The electrical power to the relay contacts should be removed before checking any
mechanical settings, to avoid any risk of electric shock.
Draw out case relays
Removal of the cover on equipment incorporating electromechanical operating
elements, may expose hazardous live parts such as relay contacts.
Insertion and withdrawal of extender cards
When using an extender card, this should not be inserted or withdrawn from the
equipment whilst it is energised. This is to avoid possible shock or damage hazards.
Hazardous live voltages may be accessible on the extender card.
Insertion and withdrawal of heavy current test plugs
When using a heavy current test plug, CT shorting links must be in place before
insertion or removal, to avoid potentially lethal voltages.
Decommissioning and Disposal
Decommissioning: The auxiliary supply circuit in the relay may include capacitors
across the supply or to earth. To avoid electric shock or energy
hazards, after completely isolating the supplies to the relay
(both poles of any dc supply), the capacitors should be safely
discharged via the external terminals prior to decommissioning.
Disposal: It is recommended that incineration and disposal to water
courses is avoided. The product should be disposed of in a safe
manner. Any products containing batteries should have them
removed before disposal, taking precautions to avoid short
circuits. Particular regulations within the country of operation,
may apply to the disposal of lithium batteries.
10
Technical Specifications
Protective fuse rating
The recommended maximum rating of the external protective fuse for this equipment
is 16A, Red Spot type or equivalent, unless otherwise stated in the technical data
section of the product documentation.
Insulation class: IEC 61010-1: 1990/A2: 1995 This equipment requires a
Class I protective (safety) earth
EN 61010-1: 1993/A2: 1995 connection to ensure user
Class I safety.
Installation IEC 61010-1: 1990/A2: 1995 Distribution level, fixed
Category Category III installation. Equipment in
(Overvoltage): EN 61010-1: 1993/A2: 1995 this category is qualification
Category III tested at 5kV peak, 1.2/50µs,
500Ω, 0.5J, between all
supply circuits and earth and
also between independent
circuits.
Environment: IEC 61010-1: 1990/A2: 1995 Compliance is demonstrated by
Pollution degree 2 reference to generic safety
EN 61010-1: 1993/A2: 1995 standards.
Pollution degree 2
Product safety: 73/23/EEC Compliance with the European
Commission Low Voltage
Directive.
EN 61010-1: 1993/A2: 1995 Compliance is demonstrated
EN 60950: 1992/A11:1997 by reference to generic safety
standards.
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