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ElectricalDiagrams
General
Single wire diagrams
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AGENDA
GENERAL
SINGLE WIRE DIAGRAMS
FUNCTIONAL DIAGRAMS
WIRING DIAGRAMS
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AGENDA
GENERAL
SINGLE WIRE DIAGRAMS
FUNCTIONAL DIAGRAMS
WIRING DIAGRAMS
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General An electric diagram is a representation of how the different parts of
a network, an installation, or a device (or group of devices) are connected and related among them.
The diagrams are classified in:
Single-wire: These diagrams show the path of current circulation, as well as the main elements of the power system (lines, buses, transformers, circuit breakers, disconnectors, surge arresters, generator, etc.). They show solely one phase of the circuit in balanced systems.
Multiwire: They are more complete than single-wire diagrams, since they present the information of every phase of the circuit.
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Functional: They also show the connections of the circuit breakers (always in open position), disconnectors (also in open position), AC and DC circuits without voltage, unexcited auxiliary relays, open AC and DC circuit breakers, signal and drive switches, etc.
Wiring: There are two kinds of wiring diagrams:
Interconnection among devices.
Internal interconnection of devices.
When elaborating a diagram, care should be taken to make it as easy to understand as possible, avoiding information that could lead to confusion.
General
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All collections of functional diagrams must show the conditions of representation and nomenclature of terminals, as following:
Conditions of representation of diagrams: Open circuit breakers. Unloaded springs.
Open disconnectors.
Unloaded AC and DC circuits.
Unexcited auxiliary relays.
Open AC and DC automatic circuit breakers.
Signal and drive switches in position “rest after opening”.
Terminal nomenclature Position switchboard, frontal.
Position switchboard, back.
Other switchboards.
Outdoors devices and boxes.
General
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AGENDA
GENERAL
SINGLE WIRE DIAGRAMS
Introduction
Symbols
Examples
Single wire diagrams of transformer substations
General diagrams and their interpretation
FUNCTIONAL DIAGRAMS
WIRING DIAGRAMS
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Single-wire diagrams It is the representation in solely one line of
two or more conductors.
Hence, it might represent:
Circuits of one-phase or multi-phase systems
Conductors with the same layout.
The line that symbolizes the conductors of a sole circuit will be crossed by as many diagonal lines as phases are in the circuit. This criterion is not applied to high voltage installations.
The single-wire diagrams can be: General
Simplified
The difference between them resides in the level of detail, minor in the seconds.
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Single-wire diagrams
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Single-wire diagrams
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Single-wire diagrams
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AGENDA
GENERAL
SINGLE WIRE DIAGRAMS
Introduction
Symbols
Examples
Single wire diagrams of transformer substations
General diagrams and their interpretation
FUNCTIONAL DIAGRAMS
WIRING DIAGRAMS
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Symbols
Opened contact
Closed contact
Disconnector 89
Automatic circuit breaker 52
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Symbols Current transformer
Current transformer with marked polarity
One-phase voltage transformer
Voltage transformer with marked polarity
One-phase voltage transformer
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Symbols
Thermal relay [49]
Hour counter
Ammeter
Voltmeter
Magneto-thermal breaker [98]
Auxiliary relay coil
Tilting auxiliary relay
Time-delay relay coil
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Symbols
Integrator
Wattmeter
Active energy counter
Varmeter
Reactive energy counter
Synchronoscope
Display
Frequency meter
Current converter
Voltage converter
Active power converter
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Symbols
Three-winding three-phase transformer
Three-winding three-phase transformer
Three-phase transformer of multiple taps with on-load tap changer
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Standard device function number (IEEE C37.2)
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AGENDA
GENERAL
SINGLE WIRE DIAGRAMS
Introduction
Symbols
Examples
Single wire diagrams of transformer substations
General diagrams and their interpretation
FUNCTIONAL DIAGRAMS
WIRING DIAGRAMS
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Examples. Low voltage motor supply The following diagram shows the installation of
a three-phase motor, with tripolar circuit breaker and three protection fuses.
The representative conductor is crossed by three diagonal lines, showing that this is a three-phase circuit.
The terminals of the fuses of each phase are indicated (1-2, 3-4 and 5-6), as well as those of the poles of each phase of the circuit breaker.
There had not been indicated the characteristics of the installation, such as rated voltage, conductors section, motor power, or fuses and circuit breaker characteristics.
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Examples. Low voltage motor supply The single-wire diagrams are
inadequate in diagrams of motor installation when they have the possibility of turn inverter, stator-resistances starter, speed variation, etc.
In these cases, the multiwire diagram is recommended, as shown in Fig.
It can be appreciated the circuit breaker Q1, two contactors KM1 and KM2 to invert the direction of rotation, a contactor KM11 to short-circuit the resistances and the three-phase motor.
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Examples. Outdoors MV transformation centre
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Examples. Indoors MV transformation centre
1. Transformer bay.2. Protection bay.3. Incoming feeder bay.4. Outgoing feeder bay.5. Low voltage switchboard.
MAIN BUS
OUTGOING FEEDERS LOW VOLTAGE SWITCHBOARD
CIRCUIT BREAKER
TRIPOLAR DISCONNECTOR
GROUNDING
TRANSFORMER
FUSE
MULTIPOLAR CIRCUIT BREAKER
TERMINAL
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AGENDA
GENERAL
SINGLE WIRE DIAGRAMS
Introduction
Symbols
Examples
Single wire diagrams of transformer substations
General diagrams and their interpretation
FUNCTIONAL DIAGRAMS
WIRING DIAGRAMS
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Single-wire diagrams of transformer substations
Symbols of circuit breakers
Circuit breaker of the manufacturer AEG,
rated voltage 72.5 kV,
rated current 1250 A
breaking capacity of 25 kA.
Besides, it is indicated as the circuit breaker number 5 of the 72.5 kV switchyard.
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Single-wire diagrams of transformer substations
SYMBOL LABEL
Double side-break disconnectors
Centre-break disconnectors
Pantograph disconnectors
General symbol (unipolar disconnector)
Symbols of disconnectors
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Single-wire diagrams of transformer substations
Two disconnectors are pictured: 89-5-1 and 89-5-2.
Both have the same characteristics:
Model: MESA "SGC".
Rated voltage: 72.5 kV.
Rated current: 1250 A.
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Single-wire diagrams of transformer substations
Symbol of surge arresters
Three Siemens surge arresters,
model EP2060-2PN
rated voltage 60 kV,
star-connected and grounded.
It has not been indicated the model of the installed discharge counter.
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Single-wire diagrams of transformer substations
Symbols of power transformers
Symbols of autotransformers
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Single-wire diagrams of transformer substations
The specifications that should appear in the diagrams for these equipments are:
The transformers are signalled by the letter T followed by the number that indicates their order inside the substation where they are installed.
The autotransformers are signalled by the letters AT followed by the number that indicates their order inside the substation where they are installed.
Power expressed in MVA or kVA.
Connection group.
Rated voltage of every winding.
Indication of the grounding connection.
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Single-wire diagrams of transformer substations
Transformer with: rated voltages 66 kV and 50
kV in the high voltage side
22 kV in the secondary
on-load tap changer, as indicated by the arrow that crosses the primary winding.
The voltage of operation is indicated by underlining.
In the transformers with no-load tap changer the following symbol is utilised:
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Single-wire diagrams of transformer substations
Current transformer symbols in accordance to different standards
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Single-wire diagrams of transformer substations
Current transformer symbols
Fig. 20
Three transformers, manufacturer
Arteche, model CXG-72, transforma-
tion ratio, delta-connected.
Fig. 21
Three current transformers, bushing
type BM, mounted inside a circuit
breaker.
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Single-wire diagrams of transformer substations
Voltage transformer symbols
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Single-wire diagrams of transformer substations
Voltage transformer symbols
Fig. 25
Three one-phase voltage
transformers removable
type with double secondary
winding:
- One star-connected.
- The other connected in
open delta.
- The primary is star-
connected and pro-
tected with fuses.
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Single-wire diagrams of transformer substations
Capacitive voltage divider symbol
The diagram also shows the equipment of the drainage coil, connected in parallel with a discharger and a disconnector, so when the drainage coil has to be disconnected the ground reference in the capacitive divider is not lost.
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Single-wire diagrams of transformer substations
Capacitor battery
Each capacitor has individual protection (fuses).
The battery has an installed power of 3600 kVAr, is star-connected and fed by an underground cable with a rated voltage of 22/ kV.
It also includes three voltage transformers for measurement and protection.
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Single-wire diagrams of transformer substations
The measurement devices in any single-wire diagram are represented by a circle, including their correspondent symbol:
Voltmeter
Ammeter
Wattmeter
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Single-wire diagrams of transformer substations
The protection relays in any single-wire diagram are represented by a circle, including their correspondent number, according to standard IEEE C37.2-1996:
Synchronism-check device
Distance relay
Differential protective relay
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SW diagrams is the simplified description of the connections among the different elements in a substation
It is defined by : Nº of transformers
Nº source and feeder lines
Buses configuration
Switching elements
220 kV
L1
EB
L2 L3 L4 T1 T2 T3
MT
10L
- - - EB1
10L
- - - EB2
10L
- - -
50MVA 50MVA 50MVA
PB
Single-wire diagrams of transformer substations
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The most used bus bar arrangements are: Single bus
Double bus
Multiple bus
Ring bus
Every bay is composed by several elements:
When the breakers are detachable it is not necessary to install isolating disconnectors
IsolatingDisconnector
By- pass Disconnector(optional)
Breaker
Single-wire diagrams of transformer substations
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The simplest arrangement is single bus
Advantages: Simple and easy operation
Very easy interconnection wiring
Reduced cost
Disadvantages: A single bus failure implies substation
blackout
Breaker maintenance implies bay outage (by-pass)
ST expansion needs de-energizing
Reliability can be improved splitting the bus and/or adding by pass disconnectors for maintenance purposes
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Single-wire diagrams of transformer substations
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“H” Diagram
Particular case of split single bus with tie breaker or disconnector. Very used in distribution or customer substations
Two possibilities, H3 (3 breaker) or H4 (4 breaker)
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Single-wire diagrams of transformer substations
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The double bus conf. has several possibilities: One breaker, two disconnectors
Breaker and a half
Two breakers
Advantages: Flexibility for circuits clustering
Bus maintenance without de-energizing
Disadvantages: More area needed. Higher cost
Breaker failure implies circuit outage
Reliability is improved with bus tie breaker: Load transfer
Line breaker outage
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Single-wire diagrams of transformer substations
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Breaker and a half: Solves the problem of breaker failure
It complicates switching and protection
Higher cost and area needs
Two breakers: Greater flexibility
Greater reliability
Higher cost and area needs
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Single-wire diagrams of transformer substations
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The ring arrangement rises reliability and flexibility
It uses the same number of breakers than circuits
Advantages: Breaker disconnection does not imply outage
Two sources for every circuit
Disadvantages: More complicated operation
More complex protections
Expansion limited
Single-wire diagrams of transformer substations
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In planning an electrical substation or switchyard facility, one should consider major parameters as discussed, Reliability
Cost
Available area
Most used arrangements: Transmission substation, double bus generally
Distribution substations,
Single bus in HV (H3- H4)
Double bus in MV
Customer substation
Single bus in HV (H3, H4)
Single-wire diagrams of transformer substations
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AGENDA
GENERAL
SINGLE WIRE DIAGRAMS
Introduction
Symbols
Examples
Single wire diagrams of transformer substations
General diagrams and their interpretation
FUNCTIONAL DIAGRAMS
WIRING DIAGRAMS
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General diagrams and their interpretation
In these diagrams, besides the power circuits, the circuits of protection and measurement are also included.
The characteristics of all represented devices (transformers, capacitor batteries, etc.) shall be indicated, including protection relays and automatisms.
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General diagrams. Transformer bay
The associated circuit breaker, 52-1, has the following characteristics: Manufacturer: Sprecher.
Model: HPF-409H
Rated voltage: 72.5 kV.
Rated current: 1600 A.
Breaking capacity: 20 kA.
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General diagrams. Transformer bay
The circuit breaker receives tripping order from the following relays: 51: Direct order.
86: Receives tripping order from the operation of the relays:
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General diagrams. Transformer bay
86: Receives tripping order from the operation of the relays: 87: Differential.
63B: Buchholz relay of pressure of the liquid of the transformer. Provides alarm and tripping for the circuit breaker 52-1 through the relay 86 and by means of its auxiliary 63BX.
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General diagrams. Transformer bay
86: Receives tripping order from the operation of the relays: 51NX: Actuates as a consequence of the operation of the relay 51N of neutral overcurrent, also providing
the corresponding alarm. The 51N relay is fed by a current transformer type BR, with ratio 300/5 A, power 15 VA and class S20 that trips over circuit breaker 52-6.
50: Instantaneous overcurrent relays fed by current transformers type BR, with ratio 300/5 A, power 15 VA and class S20.
63N: Pressure indicator relay of the liquid where the reactance TZ-1 is immersed. This relay 63N trips the relay 86 by means of its auxiliary 63NX, raising the corresponding alarm by the relay 63AX.
26: Thermal relay of overtemperature indication of the liquid where the reactance TZ-1 is immersed. It provides alarm indication but no tripping order over the circuit breaker.
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General diagrams. Bus voltage transformer
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The secondary windings of the voltage transformers are protected by automatic circuit breakers 98. The 98 in the star-connected secondary winding of voltage 0.11/ kV activates an auxiliary relay 98X. From this winding, the bus voltage measurement is obtained by means of a voltmeter of 0-75 kV connected through a voltage switch CV. Three fuses of 2 A had been installed to protect the voltmeter.
The diagram also represents a frequency automatism by the utilization of a frequency relay 81 that by means of the auxiliary relay 81X causes the automatic closing of the general circuit breakers of 22 kV.
However, the relay 81Y, auxiliary of 81, is the one to trip the general circuit breakers of 22 kV. The frequency automatism is activated by the operation of the switch 69F.
There is installed as well an automatism for the automatic reposition of voltage, for which a relay 27B has been installed, fed by the star-connected secondary winding of voltage 0.11/ kV. The auxiliary relays 27BX, 94-1 and 94-2 of the relay 27B trip the lines L-1 and L-2.
General diagrams. Bus voltage transformer