6 MAIN
DISTRIBUTION BOARDS
PART.1
GENERAL
3.6.1.1
DESCRIPTION OF WORK
- Main
distribution board(s) (DP-MM) & (DP-EMM) for low voltage (LV
Switchgear and
control gear are to be type tested assemblies comply, as a minimum, with IEC
439-1 Assemblies of Switchgear and Control Gear for voltages not exceeding
1000V a.c. and 1200 V d.c. Circuit
breakers are to comply with IEC 947 as specified. Other components, where not otherwise
specified, are to comply with the relevant IEC standards.
3.6.1 EQUIPMENT DATA:
Submit for approval
detailed description of main distribution boards and major components supported
by manufacturer's catalogues ,indicating compliance with the Standards,
equipment characteristics, details of construction ,operating data, dimensions
and weights......etc. Give details of miscellaneous
items including incoming and outgoing feeder terminal arrangement, connections
at bus bars, isolating means, earthing means, interlocks, control devices,
indicating and metering instruments etc.
3.6.1.4
TESTS AND CERTIFICATES:
Provide complete
certified manufacturer's type and routine test records, in accordance with the
Standards.
3.6.1.5 SHOP
AND CONSTRUCTION DRAWINGS
Submit drawings for
approval including, but not limited to, the following:
- Plans and elevations with indication
of built-on equipment exact dimensions and weights
- Arrangement of boards inside rooms
allocated, indicating spaces and clearances
- Arrangement of equipment inside board
- One-line
diagram of power system showing current ratings of switchgear and busbars and
types and locations of protective gear (relays, instruments, CTs, VTs etc.)
- Schematic
and elementary diagrams of control circuits
- Foundation details, grouting holes,
installation details
- Arrangement of incoming and outgoing
feeders, terminal fittinings instruments, busbar connections etc.
3.6.1.6 TECHNICAL LITERATURE:
Submit the following for approval prior to placing orders
for equipment manufacture:
Schedule of circuit breakers
application, indicating type, range features and characteristics, short circuit
ratings, time-current curves, etc.
Method of setting of protective
devices for overload, short-circuit and earth-fault currents as coordinated
with upstream and downstream systems based on the specific coordination curves
of protective devices used and specific calculated prospective short-circuit
currents at the various points
3.6.1.7
SPARE PART
Provide
as recommended by manufactures, for possible emergency replacement and/or for one year's maintenance,
including, but not limited to the following
- One
set of fixed and moving contacts for every type of replaceable (consumable)
contact set
- One operating motor and/or coil for each type
of electrically operated circuit-breaker
- two sets of each type of indicating
lights, fuses, LEDs etc
3.6.1.8 TOOLS AND INSTRUMENTS :
Provide tools and
instruments required for routine inspection and maintenance and testing of
circuit breakers and protective devices as appropriate for type of switchgear
supplied
3.6.1.8 APPROVED
MANUFACTURES:
Obtain main
distribution board from one of the following:
ABB (Egypt
(
Schnider
Group (Egypt
PART 2 MAIN
DISTRIBUTION BOARDS AND ACCESSORIES
3.6.2.1 GENERAL
REQUIREMENS
Main distribution
boards are to be dead-front type, metal enclosed, multi cubicle, floor mounted,
free standing, 600V class of service switchboards, with draw-out switchgear
manually and electrically operated, as shown on the single line diagram, with
matching vertical sections to form a continuous integral and rigid structure.
3.6.2.2 GENERAL
CONSTRUCTION:
Rigidly framed and
bolted with electro-galvanized sheet steel enclosures, minimum thickness 2 mm,
phosphatized, primed with rust inhibiting primer and finished with thermal
polymerized polyester epoxy powder coating, grey color (RAL 7703 or ANSI 61) to
approval.
Switchgear is to be
vermin, dust and rodent proof, with IP31protection to IEC 144 for indoor installations,
and is to have adequate lifting means and base-frames and be capable of being
moved and rolled into position and directly bolted to floor without additional
sills.
3.6.2.2.1.
VENTILATION:
Compartments
are to be ventilated, where required, by approved methods complying with the
Standards.
3.6.2.2.2
FASTENINGS:
Between structural
members are to be bolted.
3.6.2.2.3 EXTENSION:
Of structure and
busbars is to be possible at either end of switchboard.
3.6.2.2.4 ARRANGEMENT:
Is to permit incoming
and outgoing busbars and cables to enter enclosure as indicated on the Drawings
and connect at respective terminals without inconvenience to installation or
maintenance.
3.6.2.2.5
REMOVING CIRCUIT BREAKERS:
Suitable
arrangements and equipment are to be provided for extracting, lifting and
unloading switchgear from enclosures as appropriate for type of switchgear.
3.6.2.2.6 SPARE AND SPACE POSITIONS:
Are defined as
follows:
spare position
: fully equipped enclosure switchgear
space position : fully equipped enclosure ready to receive
switchgear.
3.6.2.2.7 BUSBARS:
To be site rated
for normal current as shown on the Drawings with 10% higher than main circuit breaker
frame size, and braced for a symmetrical rms short-circuit duty equal or
higher than main circuit breaker duty, for one second, unless otherwise
specified or shown on drawings. Busbars are to be copper of sufficient size to
limit temperature rise to the allowable insulation or equipment temperature
ratings in contact, and to a maximum of 40 deg. C above an average ambient
temperature of 40 deg. C outside enclosure. Connections and bus work are to be
bolted with copper alloy hardware, and are to be accessible for inspection and
maintenance. Contact surfaces are to
be electro-silver plated.
3.6.2.2.8 CONNECTIONS:
From busbar
to switchgear are to be rated to carry full continuous current rating of
switchgear frame and are to be insulated.
3.6.2.2.9 FULL SIZE NEUTRAL:
Is to be continuous
through all sections. Neutral bus is to
be insulated and separate from earth bus and connected to it with removable
links.
3.6.2.2.10 EARTH BUS:
To extend full
length of board, firmly fixed to each section in accordance with the
Regulations and Standards, complete with two main earthing lugs; one at each
end, and the required number of feeder protective earth connectors.
3.6.2.3 SWITCHBOARD TYPE:
Switchboard(s) to be of the
following type(s):
- Front and\or rear accessible aligned
with fixed or with drawable main circuit breaker
section (CB type as shown in schedules) and fixed group mounted MCCB
distribution section(s).
3.6.2.4
WITHDRAWABLE METAL ENCLOSED CIRCUIT BREAKER
SECTION:
Is to consist of
compartmented unit(s), stationary part with rear busbar and cable connection
compartments and front draw-out circuit breaker assembly. Partitions between sections are to be bolted
steel plate. Partitions between compartments are to be tough solid insulating
removable bolted barriers. Each unit is
to have a hinged lockable front door with grip-handle and door mounted
instrumentation.
3.6.2.4.1 DRAWOUT CIRCUIT BREAKER ASSEMBLY:
Is to be equipped
with disconnecting contacts, wheels and interlocks to prevent connecting or
disconnecting circuit breaker when in the 'open' position, and closing circuit
breaker while racking into any of the three positions; connect, test,
disconnect. Racking mechanism and rail assemble
are to be an approved worm and lever mechanism.
It is to be possible to close the unit door with breaker in any of the
three positions and when removed. An
external position indicator is to be provided. Fixed disconnecting primary
contacts are to be accessible and replaceable from the front and are to be
silver plated copper. Moving
primary disconnect contacts are to
consist of self-aligning silver plated spring pressure finger-cluster copper
contacts fitted on line and load studs of circuit breaker.
3.6.2.5 FRONT ACCESSIBLE FIXED GROUP-MOUNTED MCCB DISTRIBUTION
SECTIONS:
Are to rear align
with main section(s) and be of uniform depth, with all devices removable from
the front, and mounted on a panel board type base. Construction is to allow all
connections and maintenance to be made without rear access. Cables are to be accommodated in extra wide
vertical gutters. Sides, top and rear are
to be covered with removable screw-on plates having formed edges all
around. Front plates are to be
sectionalized and removable, covered by trims, and secured by self-tapping
screws.
3.6.2.6 AIR
CIRCUIT BREAKERS (A .C. B. )
(A TYPE ) :
Encased in high
strength, high temperature resistant, molded plastic insulating materials, for continuous
normal operation at 100% rated current at ambient temp. 40oC outside
the Panel All should be category B as per IEC 947-2 to allow max. selectivity.
Manually operated for normal functions, automatically tripped under over
current conditions. Trip power is to be
derived from main power circuit, with sufficient tripping energy to reliably
trip circuit breaker. Fixed mounted
circuit breaker is to be rear connected.
3.6.2.6.1 CONSTRUCTION:
Manually or
manually and electrically operated, as shown on the single line diagram,
with two-step spring charged stored energy mechanism, quick- make,
quick-break type, electrically and mechanically trip-free operation to prevent
maintaining circuit breaker closed against over current condition whether under
manual or automatic operation.
Electrically operated circuit breakers are to have integrally mounted,
spring charging motor mechanism. Both
manually or manually and electrically operated circuit breakers are to have
mechanical built-in charging lever and are to include open and close direct acting
push buttons. Stored energy provision is
to allow open-close-open sequence of operation without use of external energy.
As safety feature is to allow discharging stored energy without closing circuit
breaker.
3.6.2.6.2 RATING:
For breaker higher
than 1600A frame size as shown in SLD 3P, 600V, with continuous current rating
as shown on the single line diagram.(SLD) Breaker are to be rated for
symmrical rms service S.C breaking
capacity = 100% of the ultimate S.C B.C. as per EC 947.2.
3.6.2.3.6
TRIP UNIT:
To be
totally enclosed, solid state device, measuring true r.m.s values
,interchangeable for compatible frame sizes, pluggable into front of circuit
breaker, tamper-proof and with transparent, sealable cover. Trip unit is to be direct-acting trip device,
current transformer operated, with flux transfer shunt trip that requires no
external power. It is to have adjustable
ampere setting (0.5 - 1.0 times sensor rating) with adjustable long-time delay,
short-time pick-up and short-time delay, earth-fault pick-up and time delay and
over-ride instantaneous discriminator.
Current setting range is to be by replaceable elements within the
maximum frame size rating. Once removed,
circuit breaker is to remain in the trip-free position. Earth-fault trip is to be adjustable, range
up to maximum of 1200 A, with adjustable time delay between 0.1 and 0.5
seconds. Short time delay is to be adjustable
in steps, 2 - 10 times sensor rating, with settable or adjustable time band
having maximum fixed delay of 0.2 seconds.
Selective over-ride protection is to allow full sensitivity up to
interrupting capacity of circuit breaker.
3.6.2.6.4
POSITION INDICATORS:
To be positive with trip indication
target. Target indicator is to be
mechanical and is to give indication even when control power has been lost.
3.6.2.6.4. CIRCUIT-BREAKER ACCESSORIES:
Are to include the following: -
Padlocking
or key locking provisions for all positions disconnected, test, and connected,
closing blocking, open
- Overload, short-circuit, ground fault
trip LEDS
- Trip indicator and reset button
- see single line diagrams.
AUXILIARY CONTACTS:
To include N.O. and
N.C. contacts on switchgear as required, plus three N.O. and three N.C. spare
contacts
3.6.2.6.5
MOULDED CASE CIRCUIT BREAKERS MCCBs:
Are to be
generally of the thermal-magnetic adjustable type for ratings below 250- 630 A
frame size unless otherwise indicated on the Drawings. MCCBs 800 A and larger are to be electronic
solid-state trip type with true r.m.s short circuit.
3.6.2.6.5.1
CONSTRUCTION:
Totally enclosed molded
case, constructed from high quality, high temperature resistant, tropicalized molded insulating materials, for continuous
normal operation at 100% rated current at ambient temp 40 oC outside
the enclosure, provided with quick make, quick-break, trip-free switching
mechanism, manually operated by front toggle type handle and automatically tripped under over
current conditions. Multi-pole breakers are to have a common integral trip bar
for simultaneous operation of all poles.
Contacts are to be non-welding silver alloy with arc quenching metallic
devices of approved construction. Cable
terminals are to be anti-turn box lug or clamp type with set screws.
Circuit breakers
are to include on each pole a bi-metallic inverse time-delay over current trip
element for small overloads and instantaneous magnetic over current trip elements
for operation under short-circuit conditions.
Circuit breakers 250 A
3.6.2.6.5.2 THERMAL MAGNETIC:
frame size and
larger are to be equipped with adjustable instantaneous trips.
3.6.2.6.5.3 THERMAL OVERCURRENT TRIPS:
Are to be
ambient temperature compensated to allow for ambient temperature higher at
breaker than at protected circuit or device.
Compensation is to be applicable between 25 and 50 deg. C. In case of adjustable thermal settings, range
of adjustment is not to exceed maximum trip rating shown on the Drawings.
3.6.2.6.5.4 ELECTRONIC TRIPS:
For circuit
breakers 800 A frame size and larger, are to have solid state trip units with
long time delay settings at least between 0.4 and 1.0 times maximum trip
rating, short time delay range of 2 to 10 times maximum trip rating with a
maximum clearing time of 0.2 seconds, and instantaneous protection adjustable
from 5 to 10 times continuous rating.
Solid state trip units are to be insensitive to changes in ambient
temperature
Between -20
and +55 deg. C. Earth fault protection
is to be added to the trip unit where specified, and is to be adjustable
between 0.2 and 0.6normal phase current pick-up with maximum time delay of 0.2
seconds, and is to be suitable for connection to an external current sensor.
Push-to-trip button is to be provided on cover for testing the trip unit.
3.6.2.6.5.5 TRIPPED POSITION:
When tripped
automatically by over current condition, operating mechanism of circuit
breakers are to assume an intermediate position clearly indicated by the handle
between ON and OFF positions.
3.6.2.6.5.6 INTERCHANGEABLE TRIPS:
All circuit
breakers are to have interchangeable trip units.
SEALING:
Non-interchangeable
trip circuit-breakers are to have sealed covers. Circuit-breakers with interchangeable
trips are to have trip unit covers sealed to prevent tampering.
3.6.2.6.5.6 CIRCUIT BREAKER RATINGS:
Breakers are
to be non-limiter type and to be rated for symmetrical r.m.s service short
circuit breaking capacity 100% of the ultimate short circuit breaking capacity
as per IEC-947-2.
3.6.2.6.5.7 ACCESSORIES:
Circuit-breakers
are to be designed to accommodate electrical operator, control and interlocking
functions, under-voltage release, shunt-trip coils, alarm and auxiliary
switches, padlocking devices, key-lock devices, and are to be equipped with
such accessories as required on drawings.
3.6.2.7 METERING INSTRUMENTS
3.6.2.7.1 GENERALLY:
Instruments are to
be housed in enameled, square, metal cases for flush installation with scales
and markings protected and sealed.
Accuracy of instruments is to be within 2% unless otherwise
specified.
3.6.2.7.2 VOLTMETERS:
Moving iron type,
with centre zero adjuster, range 1.25 times nominal system voltage, 90 deg.
angle, size 760 x 760 mm.
3.6.2.7
.3 VOLTMETER SELECTOR SWITCH:
7-position
rotary type.
3.6.2.7
.4 AMMETERS:
Moving iron type,
with center zero adjuster, of range 2 times nominal circuit amperage, 90 deg.
angle, size 760 x 760 mm.
3.6.2.7.5 AMMETER SELECTOR SWITCH:
4-position rotary
type.
3.6.2.7.6 CURRENT TRANSFORMER (CT) :
Indoor dry type,
rated secondary current 5 A. Rated
primary current, core size and accuracy are to be determined in accordance with
nominal current of plant protected, short-circuit level and burden.
3.6.2.7.7
VOLTAGE TRANSFORMER (VT):
Provide VT's where
required, complete with primary and secondary fuses and disconnecting device.
3.6.2.8 WIRING
3.6.2.8.1 ARRANGEMENT:
Wiring is to be
modularly and neatly arranged on master terminal boards with suitable numbering
strips and appropriate cartridge type fuses where required.
3.6.2.8.2
CONNECTIONS:
Are to be made at
front of terminal board and with no live metal exposed.
3.6.2.8.3 METAL CASES:
Of
instruments, control switches, relays etc. are to be connected, by bare copper
conductors not less than 2.5 mm2 section, to nearest earthing bar.
3.6.2.8.4 CONTROL WIRING:
PVC insulated 85
deg. C. 600 V grade, and PVC sheathed for multi-core cables.
3.6.2.8.5 FERRULES:
Wires are to be
fitted with numbered ferrules of approved type at each termination.
3.6.2.9 MISCELLANEOUS
3.6.2.9.1 ANTI-CONDENSATION HEATERS:
Are to be provided
in switchboard with disconnect switch and pilot lamp.
3.6.2.9.2 SCHEMATIC AND WIRING DIAGRAM:
Is to be provided
suitably located within each cubicle.
PART3 FIELD AND INSTALLATION WORK
INSTALLATION
3.3.6.1
EQUIPMENT BASES:
Ensure that
concrete bases and foundations provided for installation of equipment are constructed
in accordance with the approved shop and construction drawings and equipment
manufacturers' drawings and that holes for fixing bolts and provisions for
passage of cables etc. are provided as required.
3.3.6.2 BUILT-IN ITEMS:
Ensure that
equipment supports, fixings and the like, and sleeves for passage of feeders
and cables which are to be built into concrete foundations, bases, cable
trenches or building structure are provided as and when required and that they
are properly installed.
3.3.3.6 INSTALL EQUIPMENT:
On concrete bases
etc., and assemble completely plumb and level, before grouting in holding-down
bolts.
3.3.6.4 SUPPORTS AND TERMINATIONS:
Install all
incoming and outgoing cable supports, cable ends and termination fittings
required for power and control cables.
3.3.6.5 SET RELAYS:
In accordance with
manufacturer's instructions and in accordance with an approved scheme.
3.3.6.6 MAKE GOOD:
Damaged painted
surfaces, clean and apply rust-inhibiting prime coat and two finishing coats of
approved enamel upon delivery of equipment to site and as required by the
Engineer.
PART4 INSPECTION AND TESTS ON SITE
3.6.4.1 INSPECT EQUIPMENT:
Upon delivery to
Site and report any damage to the Engineer.
3.6.4.2 INSPECT AND CHECK SWITCHGEAR:
For completeness,
component ratings, types, sizes, and wiring connections. Check phasing of busbars, contacts and
clearances.
3.6.4.3 TESTS:
After installation
and before handover, carry out all tests required by the governing codes and
any other tests the Engineer may require to check compliance of the
installation with the Specification, including insulation resistance tests and
operational tests.
3.6.4.4 CHECK MAIN
AND CONTROL CIRCUITS:
Using 1000 V megger
(2000 M-ohm range) for insulation resistance between phases, between phases and
earth/enclosure and between neutral and earth.
3.6.4.5 PRIMARY INJECTION TESTS:
Provide portable
test equipment to test time-delay characteristics of circuit-breakers by
simulating an overload or fault condition.
Measure and record all test results and ambient conditions and compare
with manufacturer's data.
3.6.4.6 TEST INSTANTANEOUS TRIP ELEMENTS:
By high current
primary injection, using high-current primary injection test-sets and report
all readings.
3.6.4.7 FUNCTION TEST
Applying the
electrical function test including the electrical and mechanical operation in
the specification and show in the single line diagrams.
PART 5 MAINS FAILURE AUTOMATIC TRANSFER SWITCH
(ATS)
Type wall or floor
mounted, galvanized sheet steel cubicle of equal construction to control
cubicle, comprising circuit breakers, controls necessary for automatic
transfer of power supply from normal source to stand-by source, voltage sensing
control relay and time delay relays to signal generator start and stop,
auxiliary switches and indicating lights etc. as necessary for the required
operation shall be mechanically head type. The interlock should be electrically
& mechanically.
OPERATION:
When the voltage
and/or frequency of any phase drops below an adjustable setting (60% - 90%) of
normal supply, for an adjustable period of 1 - 300 seconds, power failure relay
is to actuate engine starting control, whilst normal mains C.B is to open. After an adjustable period (0 - 10 sec) from
sensing stabilized rated voltage and frequency of generator at the ATS, the
emergency C.B is to close. Upon
restoration of normal mains supply to above 95% of rated volt age and/or
frequency, for an adjustable preset period of 2 - 10 minutes, emergency C.B. is
to open and normal mains contactor is to close.
SELECTOR
SWITCH:
Is to have the
following positions:
Off :
both C.B.S open and remain open
Normal
: C.B.S for normal power source closes and remains closed emergency : contactor for stand-by power source closes and remains closed
Auto : automatic transfer as described above
PILOT LIGHTS:
Are to indicate
which C.B is on
.
INSTRUMENTS:
Are to include
voltmeter and ammeter with selector switches.
WIRING:
Moisture and heat resistant,
PVC insulated, stranded copper conductors, modularly and neatly arranged and
terminated on master terminal blocks
with suitable numbering strips and appropriate cartridge type fuses where
required. Flexible wiring is to be used
on all hinged/draw-out components METAL CASES: Of instruments, control
switches, relays etc. are to be connected by flexible protective conductors, of
not less than 2.5 mm2 section to nearest earthing bar or terminal.
EARTHING:
Earthing bar is to
be provided for connection of earthing and protective conductors.
FERRULES:
Wire ends are to be
fitted with numbered ferrules of approved type at each termination
SPECIFICATION FOR VARIABLE SPEED DRIVE
NOT INCLUDED IN THIS CONTRACT
The variable speed
drive shall be used to vary the speed and therefore the flow of the domestic
water pumps.
The motor speed
variation shall be performed by varying the frequency and voltage. The driving
law shall be specially adapted to match the motor available
Torque with the
pump torque characteristics (quadratic torque law). Three adjustable skip
frequencies shall be available in the speed drive to prevent operating the pump
at speeds where mechanical resonance occurs. The variable speed drive controls
shall be carried by using 24V static inputs for the logic signals and 0-10V or
4-20 mA for the analog signals.
Alarm signals shall
be on a voltage-free relay contact withstanding switching inductive loads of
1,5 A under 250 Vac. Inputs and outputs shall be user configurable to allow for
various control schemes to be used. The frequency set point accuracy shall be
of 0.05 Hz for 50Hz set point. The analogue outputs shall be configurable 0-20
mA or 4-20 mA with an accuracy of + 0.5% full scale and linearity + 0.1%.
Protections:
The variable speed drive
shall be capable of protecting itself and the
Motor
against:
Motor
overload
Motor
phase failure
Internal short-circuits
Phase
to phase and phase to ground
Variable speed drive overheating
Loss of supply phase
Supply
over voltage and under voltage
Internal short
circuits in the Variable Speed Drive.
Performance:
The Variable Speed Drive
the motor nominal
current for a period of 60 seconds. The Variable Speed Drive
Environment:
The Variable
Speed Drive
The variable speed
drive shall withstand vibrations and shocks as per IEC 68- 2-6 and IEC 68-2-27.
End Of this Section
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