PS_report_auxpowersupply_07_05_31
DB International GmbH
Libyan Railway Project
Pilot Section Al Khoms
Design Report /
Auxiliary Power Supply RPEMB
Libyan Railway Project
Pilot Section Al Khoms (Harbor – Sleeper Factory)
Design Report Auxiliary Power Supply
DB International GmbH
Libyan Railway Project
Pilot Section Al Khoms
Design Report /
Auxiliary Power Supply RPEMB
Table of Content
1...Introduction.. (4)
2...Concept (5)
2.1........General. (5)
2.2........Medium Voltage System (MV) (5)
2.2.1General (5)
2.2.2Transformer Load-Centre Substations (7)
2.2.3Medium Voltage Switchgear Section (MVS) (8)
2.2.4Resin-Cast Transformer (8)
2.3........Low-Voltage (LV) System and Switchboards.. (9)
2.3.1General Explanations / Possible Net Configurations (9)
2.3.2Applicable LV System Configuration (13)
2.3.3Standby Units (15)
3...Illumination. (20)
3.1........General.. (20)
3.2........Selection of Lamps (21)
4...Container Yard.. (22)
4.1........General.. (22)
4.2........Container Type 1. (22)
4.3........Container Type 2. (22)
4.4........Container Type 3. (22)
4.5........Container Type 4. (23)
4.6........Container Type 5. (23)
DB International GmbH
Libyan Railway Project
Pilot Section Al Khoms
Design Report /
Auxiliary Power Supply RPEMB
4.7........Container Type 6. (24)
5...Cable Crossings.. (25)
6...Point Machines. (26)
7...Earthing System.. (27)
7.1........Introduction (27)
7.2........Basic Rules. (27)
7.3........Public TN-System (27)
7.3.1Protection Measures (non-electrified railway line) (27)
7.3.2Protection Measures (electrified railway line) (29)
7.4........Public TT-System (30)
7.4.1Protection Measures (non-electrified railway line) (30)
7.4.2Protection Measures (electrified railway line) (30)
7.5........Medium Voltage Substations (not-electrified line). (31)
7.5.1General (31)
7.5.2Main Equipotential Equalization (32)
7.5.3Additional Potential Equalization (APE) (33)
7.6........Medium-Voltage Substation (electrified line) (34)
7.7........Drawings.. (36)
DB International GmbH
Libyan Railway Project
Pilot Section Al Khoms
Design Report /
Auxiliary Power Supply RPEMB
1 Introduction
Auxiliary power supply defines the electric power supply exclusively traction power as the latter is only in connection with electric train services.
The design report therefore concerns design proposals for auxiliary power supply facilities along the pilot Section Al Khoms of the Libyan Railway. It covers the line between the harbor of Al Khoms and the sleeper factory next to Wadi Ka’am with the two stations Al Khoms and Wadi Ka’am.
The pilot project can be subdivided into the following main components:
( 1 ) a construction yard in the area of Al Khoms
( 2 ) an existing port
( 3 ) an existing sleeper factory
( 4 ) the existing cement factory
The auxiliary power supply will be based on the temporary construction conditions but will also consider that the pilot section later on will be integrated into the future High-Speed Line Tripoli – Misratah. The design for the auxiliary power supply for station facilities of Al Khoms and Wadi Ka’am will be subject to a later design.
DB International GmbH
Libyan Railway Project
Pilot Section Al Khoms
Design Report /
Auxiliary Power Supply RPEMB
2 Concept
2.1 General
The design describes basically functions for utilities of the auxiliary power supply for ?Construction yard and workshop
?Utilities within the construction yard, workshop and all structures and compo-nents that are required to keep the construction of yard and sites in function. The auxiliary power supply design (APD) can be subdivided into:
a. Medium-voltage system (three-phase 11 kV, AC)
b. Low-voltage system (three-phase 400 V / 240 V, AC)
c. Standby power supply on specific locations
d. Uninterruptible power supply (UPS)
The design proposals are based on the temporary operation requirements of the stations, yard, workshop etc. but will also allow to a later stage to be modified without major problems.
2.2 Medium Voltage System (MV)
2.2.1 General
Al Khoms presently is a location where in a first step the construction yard with mainly tempo-rary facilities will be established. The primary auxiliary power supply shall mainly be provided by the public network and here most preferably by three-phase AC , 11 kV respectively 20 kV if available.
Two infeed cables shall be installed. That arrangement enables changing i.e. from infeed 1 to infeed 2 if infeed 1 fails and vice versa.
DB International GmbH
Libyan Railway Project
Pilot Section Al Khoms
Design Report /
Auxiliary Power Supply RPEMB
Figure 1: Simplified representation of main and subsidiary substations
DB International GmbH
Libyan Railway Project
Pilot Section Al Khoms
Design Report /
Auxiliary Power Supply RPEMB
The main substations shall be placed closely to the workshop location. One transformer of the main substation is foreseen for the workshop facilities. Cable feeders as shown on figure 1 shall feed other transformer stations that are also closely to their specific load centres. That enables power supply with relatively small cable cross sections and short cable lengths.
2.2.2 Transformer Load-Centre Substations
Transformer load-centre substations (TLCS) are normally used for decentralized power distribu-tion of medium voltage (MV) supply to large buildings, industrial plants, workshops, manufactur-ing premises etc.
Advantages
( 1 ) Installation in generally accessible (indoor) working areas that are:
?Appropriate enclosure of the electrical equipment
?Measures incorporated in the components of the substation to ensure
staff safety
( 2 ) Environmental accessibility by using i.e. resin cast transformers. These transformers shall withstand a continuous overload of up top 140% of the rated power with forced air-cooling, affording a power reserve to meet protracted load surges or emergency opera-tions without transformer overrating
( 3 ) Small space requirement
( 4 ) Simple project planning with standardized and type-tested components
Construction
The TLCS shall be assembled from the following components:
( 1 ) High-voltage (HV) / medium-voltage (MV) switchgear
( 2 ) Resin-cast transformer in a transformer cubicle or equal
( 3 ) Low-voltage (LV) main switchboard.
DB International GmbH
Libyan Railway Project
Pilot Section Al Khoms
Design Report /
Auxiliary Power Supply RPEMB
Figure 2 : Basic circuits of a transformer load-centre substation
2.2.3 Medium Voltage Switchgear Section (MVS)
The MVS shall be of a sheet-steel cubicle for radial feeder cable. Also ring feeder cable ar-rangements might be possible.
In case of a radial feeder cable connection it shall contain an equipment assembly comprising a transformer switch-disconnector (see above figure 2) with fuses incorporated for short circuit protection. In case of a ring feeder cable connection, two switch-disconnectors shall be added. An Earthing arrangement shall be provided on the transformer and cable switch-disconnectors in form of earthing sockets and an earthing spike.
The switch-disconnectors shall be fitted with auxiliary switches for the purpose of interlocking as a protection against incorrect switching. Also attaching mechanically interlocked fault-making switches on the cable switch-disconnectors is possible.
The switchgear section shall be equipped with a pressure relief duct into the back of the switch-gear section discharging upwards in an event of fault.
2.2.4 Resin-Cast Transformer
The use of a resin-cast transformer is recommended. Its insulation might consist of a mixture of epoxy resin and quartz powder. This environmentally acceptable material would make the wind-ings maintenance-free, moisture-proof and self-extinguishing.
With the transformer installed in the cubicle, the rated performance with AN operation (natural air cooling) and with AF operation (forced air cooling) if the roof fans are switched off , must be reduced by about 10%.
In AF operation with the roof fans switched on, the transformer shall be operated at 140 % of its rated power. That means, the transformer can be rated for the normal load, while peak loads or emergency operation can be covered by forced air cooling.
DB International GmbH
Libyan Railway Project
Pilot Section Al Khoms
Design Report /
Auxiliary Power Supply RPEMB
Using liquid-cooled a transformer means (oil-immersed) require more space for a resin-cast transformer. Additionally, an oil-collecting pit is required, whose volume corresponding to the oil content of the transformer. However, the use of an oil-cooler transformer is also possible.
2.3 Low-Voltage (LV) System and Switchboards
2.3.1 General Explanations / Possible Net Configurations
Introduction
Electrical installations are subject to comprehensive safety requirements, which are also aimed at the protection of life and limb and of property wherever electrical energy is used. Standards normally distinguish between two important areas:
a. The constructional requirements for equipment and
b. The installation requirements for electrical systems.
The explanations on the net configurations as above mentioned are based on installation re-quirements for electrical power systems with rated voltages up to 1000 V. An important aspect of these requirements is represented by measures which prevents the occurrence or persis-tence of dangerous touch voltages. These might be internationally defined as > 50 V AC or 120 V DC.
Protection against Contact
There is a distinction between:
( 1 ) Protection against direct contact
Defined to prevent contact with parts which are live during operation (active parts) and ( 2 ) Protection against Indirect Contact
Defined to prevent contact with conductive parts which do not belong to operation circuit but which can assume a potential earth under fault conditions; these parts are the “ex-posed conductive parts” of the equipment.
System Configuration
The following explanations are given on the configurations of normal three-phase systems to which the method of protection against indirect contact is related.
The power systems are described by letter symbols, which have the following significance:
First Letter:
Relationship to earth of the power source
T One point in the system is directly earthed
DB International GmbH
Libyan Railway Project Pilot Section Al Khoms Design Report /
Auxiliary Power Supply RPEMB
I
All active parts are isolated from earth or one point in the system earthed through imped-ance Second Letter:
Relationship to earth of exposed conductive parts of the electrical installation: T Parts directly earthed, independently of any earthing of the power source N
Parts connected directly to the functional earth
Further Letters:
Arrangement of protective and neutral conductors in the TN system S Separate conductors for protective-conductor and neutral-conductor functions
C
Protective-conductor and neutral-conductor functions combined in one (PEN) conductor
Find some typical system configurations as follows:
Figure 3 :
TN-C system
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Libyan Railway Project Pilot Section Al Khoms Design Report /
Auxiliary Power Supply RPEMB
The neutral and protective conductor functions are combined in a single conductor (PEN) throughout the system
Figure 4 : TN-S system
The separate neutral conductor and protective conductor throughout the system
Figure 5 :
TT system
DB International GmbH
Libyan Railway Project Pilot Section Al Khoms Design Report /
Auxiliary Power Supply
RPEMB
In the TT system is one point directly earthed (functional earth); the exposed conductive parts of the electric equipment are connected to earthing electrodes which are separate from the func-tional earth.
Figure 6 :
IT system
The IT system has not direct connections between active and earthed parts; the exposed con-ductive parts of the electric equipment are earthed
Figure 7 :
TN-C-S system
The neutral and protective conductor functions are combined in a single conductor, the PEN conductor in part of the system only.
DB International GmbH
Libyan Railway Project
Pilot Section Al Khoms
Design Report /
Auxiliary Power Supply RPEMB
2.3.2 Applicable LV System Configuration
The LV system will be three-phase AC, 400 V / 240 V to be provided from transformers most preferably placed in the load centres. That means, the transformers and the LV main switchboards will be located where many equipments are in operation.
Switchboards with rated currents up to bout 4000 A are mostly installed as main switchboards wherever large power consumption has to be catered for. Figure 2 shows a logical division of a power supply system into a ‘main switchboard ‘ power centre directly supplied from a trans-former, whose infeed, outgoing and busbar coupling switches consists only of circuit breakers.
DB International GmbH
Libyan Railway Project
Pilot Section Al Khoms
Design Report /
Auxiliary Power Supply RPEMB
Figure 8: Typical configuration of a low-voltage system
The various ‘sub-distribution boards’ supplying a wide variety of loads. The separation between the high-current main switchboard and the following ‘sub-distribution boards’ has a number of advantages:
DB International GmbH
Libyan Railway Project Pilot Section Al Khoms Design Report /
Auxiliary Power Supply
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L 1L 2L 3N
PE
( 1 )
The main switchboard shall normally be installed in the immediate vicinity of the infeed transformators. Cables and busbar connections therefore are short:
( 2 )
Circuit breakers incorporated in it for infeeds, outgoing feeders and busbar couplings shall be limited to a single form of construction
( 3 )
Circuit breakers shall be designed as withdrawable units that saves one disconnector for each circuit breaker
( 4 )
Sub-distribution boards shall be placed centrally in relation to their loads with the in-tended purpose to keep cables short in lengths
Low voltage switchgear shall be arranged as TN – S net-type. That prevents, in case the line is electrified, that traction power return current would enter the low voltage system.
Figure 9: Typical TN-S system; separate neutral conductor and protective conductor throughout the system 2.3.3 Standby Units General
Standby units are required to maintain continuity of the supply load wherever the necessary or stipulated security of the system is not guaranteed by the public supply system. That means if the public power supply is often not available continuously over 24 hours, the standby unit shall most probably supply the basic load for the time of the public network failure.
DB International GmbH
Libyan Railway Project
Pilot Section Al Khoms
Design Report /
Auxiliary Power Supply RPEMB
At the present situation, the project line will not have signalling equipments and only a few track switches shall be operated electrically. The various containers might have power supply for illu-mination, motors, air-conditioning etc. as well as the trackside illumination.
The workshop as planned for the construction yard might also have equipments like machinery, air conditioning, fuelling station for diesel locomotives and permanent way maintenance vehi-cles, point machines, etc. Therefore it is recommended to establish a stationary standby unit. The capacity of the unit depends upon the load of machinery that shall be available all times but shall consider possible breakdown times as experienced in the past. The standby output shall be connected with the busbars of the 400 V / 250 V AC side which means that the standby unit output is low voltage three-phase level only. Also a voltage level of 11 kV respectively 20 kV is possible, but requires higher investment.
Usually, the public supply system shall have a very high availability, but the supply failure of supply can nevertheless not be excluded.
Motor-generator Set (MGS)
MGS units are in use to provide electric energy on building sites and out-of-way premises that cannot be connected to the public supply system and standby supplies in the event of failures of the public system. In the present case, standby units shall be provided in two types.
Type 1 : is a mobile standby unit with a combustion motor and a three-phase generator with performances up to 50 kVA. The unit will only be used for a limited time and on the low-voltage supply of i.e. an individual container / small building or on small equipment. Starting of the unit will be manually. The supply shall be three-phase 400 V / 250 V AC 50 Hz; units with power supply of Single-phase AC with 250 V 50 Hz but small loads might also be available. Containers or buildings shall have a three-phase and a single-phase socket to attach a standby unit if required.
Type 2 : is a stationary MSG with performances according to the required loads for i.e. a workshop and for a limited time period. However, the unit shall be suitable also to operate one day on full performance. The unit shall start automatically if the public power breaks down but shall shut the generator automatically down if the public supply is restored again. The unit shall have its full capacity after about 6 to 15 seconds. The voltage level of the three-phase AC sup-ply shall be of the standard 400 V / 240 V.
The unit shall have two tank facilities; a depot tank shall contain a two-week supply, the other tank shall have its daily fuel demand. Refilling of the daily tank from the depot tank shall proceed automatically.
The motors of the standby units shall be water-cooled
The following figure shows schematically a standby unit with normal automatic operation.
DB International GmbH
Libyan Railway Project
Pilot Section Al Khoms
Design Report /
Auxiliary Power Supply RPEMB
PUBLIC SUPPLY
Figure 10 : Schematic arrangement of a DSG with automatic operation Approximate room sizes required for DSG are as follows:
Generator power 20 to 60
kVA
100 to
200 kVA
250 to
550 kVA
650 to
1500 kVA
Length 5.0 m 6.0 m 7.0 m 10.0 m Width 4.0 m 4.5 m 5.0 m 5.0 m Height 3.0 m 3.5 m 4.0 m 4.0 m Door width 1.5 m 1.5 m 2.2 m 2.2 m Door height 2.0 m 2.0 m 2.0 m 2.0 m
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Libyan Railway Project
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Auxiliary Power Supply RPEMB
Static UPS Systems
Static uninterruptible power-supply systems are employed when a reliable high-quality power supply is necessary for sensitive loads. They are used for single-phase loads up to about 70 kVA and for three-phase loads up to 1000 kVA and beyond.
They are incorporated into supply systems for data processing equipment, process control, power network supervisory systems, medical equipments, operational centres of police forces, fire departments, radio relay stations and particularly important manufacturing plants or work-shops.
A UPS system consists of:
o a
rectifier,
o a battery bank,
o an inverter and,
o a static by-pass switch.
This arrangement applies to both single-phase and three-phase systems.
An example shall describe the function of an UPS as follows:
( 1 ) The absolutely interruption-free power supply shall be afforded by the now-customary technique in which static converters systems are in continuous operation.
( 2 ) Continuous operation means that with the public supply is healthy the power is continu-ously supplied to the load through the rectifier and the inverter. In this mode of operation, the rectifier
( 3 ) In this mode, the rectifier shall fulfil two functions:
a. the supply of power to the inverter,
b. charging or float-charging the associated battery set.
( 4 ) The battery shall be used in the standby parallel mode – i.e. in normal operation it is in the floating condition and on failure of the public supply it supplies the inverter without a break and without any switching operation.
( 5 ) The inverter shall draw its power from the DC link and supplies single-phase or three-phase power at its output, depending on the system.
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Libyan Railway Project Pilot Section Al Khoms Design Report /
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RECTIFIER
BATTERY INVERTER MANUAL BYPASS
SECURE BUS
( 6 )
A bypass switch shall be provided to allow manually bypassing the system in case of maintenance, servicing etc. It switches directly from the public supply to the so-called ‘secure bus’ that is the busbar section to be supplied by the UPS.
Figure 11: Typical Block diagram of an UPS
Normally, UPS systems are integrated in systems with sensitive purposes like, control and measuring facilities. Their battery volume shall be sufficient to cover a time period of about 10 minutes breakdown without loosing data or commands. After that time, the regular or standby power supply shall take over. In case a UPS is required – for heavy load, the battery capacity shall be big enough to supply power by battery and inverter for about 5 hours time. That how-ever, should be decided during design stage.
DB International GmbH
Libyan Railway Project
Pilot Section Al Khoms
Design Report /
Auxiliary Power Supply RPEMB
3 Illumination
3.1 General
Illumination of the track area in the construction yard shall be illuminated with a mean illumina-tion brightness of an E m about 10 lx; the measuring level is about 0.2 m above ground level. The following table – derived from the European Standards prEN 1264-2 shows important illumina-tion parameters for railway facilities:
Zone Classification E m
lx
U GRL Ra Remarks
Incoming
/outgoing tracks and switches Railway facilities,
zone of switches
etc.
10 0.4 50
20
Train arrangement groups Railway facilities,
zone of switches
etc.
10 0.4 50
20
Loco parking places Railway facilities,
zone of switches
etc.
10 0.4 50
20
Service area with refuelling station and sanding sta-tion Railway facilities,
zone of switches
etc.
20 0.4 50
40
Parking and walk-
ways around the depot / station buildings Medium traffic
density
10 0.25 50
40
Remarks
U : Continuity of illumination brightness
Ratio of the minimum illumination brightness and the mean illumination brightness
at a defined area
E m : Maintenance value
Value that shall not be less than the mean illumination brightness on a defined
area
Ra : Index of colour rendition