SECTION 6: LV MAINS & SUB-MAINS CABLING

Atelier Management and Design Consultancy (Vietnam) Co., Ltd SEL6-GENERATING SETS/1

SECTION 6: GENERATING SETS6.1 GENERAL6.1.01 Functional description

The generator scope of work covers the supply and installation of a standby generating set. The generator is to be fully enclosed in an acoustic enclosure and is to be installed within the main building. They will normally be on standby duty and available for instant start up on receipt of a signal or operate under local manual control for testing purpose.

6.1.02 Cross referencesGeneral

Comply with the General requirements worksection.

Related worksections

Refer to the following worksections:

Adhesives, Sealants, Fasteners, Service Trenching, Switchboards, Switchboard Components, Acoustic & Vibration Control, Power Cables, Electrical Commissioning, Mechanical Piping, Tanks & Vessels, Mechanical Controls

6.1.03 Standard

6.1.04 Referenced document

To BS 4999/ 5000

6.1.05 Interpretation

Technical

Generating sets to be PRIME RATED. For reference the following definitions are used.

Net continuous rated output: Net continuous electrical output available at alternator terminals, not including the electrical power consumed by the generating sets dependent and essential auxiliaries.

Net prime rating: Net continuous 70% electrical output available at alternator terminals, not including the electrical power consumed by the generating sets dependent and essential auxiliaries.

Net short-time rated output (or stand-by rating): Net electrical output available from the generating set for 1 hour in every 12 hours at net continuous rated output, not including electrical power consumed by the generating sets dependent and essential auxiliaries.

Start response time: Total elapsed time from receipt of start signal to final connection to load.

All rated output to be designed tropically at minimum temperature 400C.6.2 QUALITY

6.2.01 Inspection

Notice

Give sufficient notice so that inspections may be made of each complete generating set and associated systems at the manufacturers or suppliers factory before delivery to the site. Note the generator and alternator are to be assembled in the manufacturers factory.

6.2.02 Pre-completion testsProduction tests

Generating sets: Carry out acceptance tests to TCVN.Alternators: Carry out performance tests to TCVN.6.2.03 Submissions

Product data

Submit product data for test, manual and auto modes, including the following:

Technical description and specifications of each generating set, including output curves for base load and stand-by conditions, alternator and engine data, automatic voltage regulator, synchronising and load sharing modules and auxiliaries.

Type test reports as follows:

Generating sets: To BS 4999/ 5000

Alternators: To BS 4999/ 5000

Net continuous rated output.

Net short-time rated output.

Transient and subtransient reactance of the alternators.

Voltage regulation grade.

Generating set efficiency at 50%, 75% and 100% load.

Calculations for performance of acoustic enclosures and silencers.

Evidence that the engine type has previously passed cold starting tests at the minimum ambient site temperature.

Clarify that the offered generating sets have sufficient immunity to the UPSs, variable speed drives and miscellaneous solid state drives throughout the facility.

Shop drawings

Submit shop drawings indicating the following:

Maximum mass and overall dimensions of each separable assembly.

Access clearances for operational maintenance and dismantling.

Electrical single line diagram and general arrangement for the complete system.

Control diagrams.

Alarms and shutdown annunciator text engraving schedule.

Details of foundations and anti-vibration mountings.

Vibration frequencies & amplitudes.

Physical layout of generators, day tanks, pumps etc

Location of control & starting batteries.Certify

Certify by the manufacturer that the offered generating set will operate as specified in the installation as shown on the drawings.

Certify by the manufacturer that the acoustic performance of the generating set in the specified acoustic enclosure.

6.3 COMPONENTS

6.3.01 General

Electrical output

380 V, 3 phase, 4 wire + earth, 50Hz, star connected with neutral terminal.

Engine

4 stroke cycle watercooled diesel, on radiator onboard.

Generator Performance

Include means to ensure adequate and reliable voltage build-up on start-up.

Be capable of providing stable voltage within 6 percent of the rated values prior to the operation of the changeover devices.

Comply with voltage regulation characteristics for Class VR2.22 as defined in BS 4999/ 5000.

The variation in voltage (r.m.s.) does not exceed 20 percent of the nominal system voltage for the maximum load step likely to be imposed when the generator set is in service; and within 10 s, the voltage returns to providing stable voltage within 6 percent of the rated values.

The alternating current generator and exciter shall be continuously rated and capable of supplying the load to which it is connected so that temperature rises will be in accordance with BS 4999/ 5000 for the winding materials utilized.

6.3.02 Alternators

Voltage waveform

Sinusoidal, with total wave form deviation not exceeding 5 %.

Excitation

Permanent magnet.

Overspeed withstand

A speed of 1.2 x unit rated speed for both alternator and engine.

Alternator underspeed withstand

Normal operation at net continuous rated output at a speed of 0.95 x unit rated speed, without overheating.

Sustained short-circuit withstand

At least 2.5 x full load steady state short-circuit current, for at least 5s.

Number of poles

4.

Enclosure classification

Drip proof IP22, with screened ventilation openings.

Cooling method classification

Class IC01, to BS 4999/ 5000.

Insulation classification

Class H with tropicalization and anti abrasion to IEC 60085.

Anti-condensation heaters

General: Provide at least 2 anti-condensation heaters within the winding enclosure.

Rating: Rate heaters to maintain the windings and insulation at least 6oC above ambient temperature when the alternator is at rest and one heater is in service.

Location: Locate a heater at each end of alternator windings in a position which allows heat transfer to the winding insulation by convection, without exceeding maximum allowable insulation temperature. Do not fix heaters to windings.

Terminations: Connect heaters to separate identified terminals within a separate accessories terminal box which is connected to a permanent supply.

Connection diagram: Provide a connection diagram for the heaters. Locate within the terminal box.

Winding thermistors

General: Provide thermistors to alternator stator windings.

Standard: To BS 4999/ 5000

Thermistor type: Positive temperature coefficient.

Thermistor temperatures:

Engine shutdown: 160oC.

Winding temperature high pre-alarm: 140oC.

Terminal boxes

Construction: Provide metal terminal boxes. Size to allow the current transformers, power and control cables and cable lugs to be neatly installed and terminated with necessary clearances between live parts and the box, and without placing undue strain on termination points.

Supply cable terminal box: Provide removable lid and side covers.

Terminals: Provide star connected windings. Bring both ends of each winding out to separate terminals. Establish a neutral terminal.

Sealing: Provide neoprene or bonded cork gaskets between terminal boxes and their frames and covers.6.3.03 Engines

General

Engine: 4 stroke cycle watercooled diesel engine.

Sizing: When sizing the engine, take into account the nature of connected loads including auxiliaries, harmonics and transient operation

Continuous rating of the diesel engine shall not be less than maximum power demand. Maximum power demand is the sum of:a. Maximum continuous base load rating of the generator at rated speed and design temperature at 0.8 PF lagging, 380V, three phase, Wye connected, 50Hz as specified.

b. Transmission losses (if any).

c. Auxiliary power take- off.

d. In addition the diesel unit shall be capable of running at 110% of continuous rating for one hour in every twelve hours. The declared continuous nett brake power shall be in accordance with ISO 3046/1. The Supplier shall calculate any derating for site condition in accordance with ISO 3046/1.

Bearings: Provide front and rear main bearings, so that crankshaft alignment is not affected by dismantling of the alternator.

Cooling system

The cooling system shall be of the radiator type. Engine coolant shall be treated water or similar medium.

The radiator shall be mounted on a common skid, with guards to prevent accidental contact of personnel with fan or hot radiator parts. The tubing connecting to the radiator and engine shall be supplied and installed. The fan shall be driven by engine thru a coupling or belt.

The radiator shall be sized for operating under the required maximum design ambient temperature plus 10%.

Fuel System

The supplier shall provide a diesel tank for installation. The capacity of the tank shall be sufficient to permit the emergency generators to run at full rated capacity for a continuous 24-hours period. Additionally the tank shall be sized to allow for any additional fuel cooling requirements. A calculation sheet shall be provided to confirm storage tank capacity. The diesel storage tank shall be provided with the equipment and services listed as follows:

Externally mounted level gauge with test provision

High and low level alarms (note connection to BMS)

Vent to atmosphere

Drain valve

Overflow connection

Diesel inlet with automatic filling device

The fuel suction filters shall be of the duplex type with replaceable elements and a changeover facility to permit removal and replacement of either element without need for engine shutdown. Filter mesh size shall be specified by the engine manufacture.

Provision shall be made for priming and bleeding the fuel injection system.

Fuel line between injection pump and injectors shall be heavy seamless tubing arranged to eliminate irregularity of fuel injection, and preferably be of the same length to all cylinders. Fuel lines shall be adequately supported and routed to follow the engine contour as closely as possible.

Lubrication System

A pressure lubrication system shall be provided using a gear type, gear driven lube oil circulation pump. The pump shall be located on the engine crankcase. Oil pressure shall be controlled by a pressure regulator in the pump discharge. The oil filter shall be of the replaceable element type and shall be capable of removing particles 12 microns and larger with a clean pressure drop not exceeding 0.3 barg. The filter shall be of duplex type with manual changeover facility and shall be equipped with relief valves and a differential pressure gauge.

Provide a blow-by gas control for recirculation of vent gases.

Exhaust System

Provide the engine exhaust bifurcation piece complete with bellows expansion joints, the exhaust silencer complete with a right angled bend transition piece, integral spark arrester, spark trap, specified fittings and stainless steel bellows expansion joints, and all interconnecting pipe / ductwork up to the final exhaust termination point on the roof.

The exhaust silencer shall be sized to match the engine requirements at 100% load. The exhaust system shall be fully insulated for personnel protection. Support of the complete exhaust system shall be installed.

Provide pressure drop calculation for actual exhaust pipe.

Maximum allowable back pressure in the exhaust system shall not be greater than 0.05 barg for the total exhaust system. Provide calculation for pressure drop.

Governing

General: The engine shall be provided with electronic controlled governors which enable engines to operate continuously at 1500r/min from no-load to the maximum rated electrical load connected to the alternator. Provide filters which ensure that harmonics or switching spikes generated by the load do not interfere with the operation of the governor, overspeed or underspeed cut out devices.

Governing accuracy: Class A1, of ISO 3046, Part 4

Governor adjustments: Provide adjustment settings for

speed droop between 0 percent and 5 percent;

stability;

maximum speed;

acceleration rate; and

load gain.

6.3.04 Operation

General

Provide automatic and manual modes to start and shut down generating.

In automatic mode the generator is to commence operation in the event of power failure and provide power within 20 seconds.

Note that the generators are required to drive variable speed drives. The generators are to be selected to match the characteristics of these equipment.

Manual sequence control

Provide controls to manually start and shut-down the generating set. Include emergency stop, meters, selector switches, and status indicating lights.

Automatic start control

Provide for the following:

Upon receipt of a start signal, for generating set to start automatically, come on-line and connect to the load.

Connection of alternators.

Shut-down of machine.

Automatic engine shutdown

Provide for generating set to run to suit the load demand until receipt of the mains restored signal is received. At this point the automatic engine shut-down signal must be activated after an adjustable time delay of 030min.

Engine shutdown

Provide a shutdown control system which disconnects the alternator, and shuts down the engine upon the occurrence of fault conditions, such that

engines cannot be restarted before safety devices have been manually reset and system alarm sensors have returned to the normal state;

the overspeed shutdown acts directly to disconnect the fuel supply independent of the governor; and

the shutdown control system may be reset by the operation of one reset switch, after safety devices have been manually reset.

Emergency and fault shutdown

Provide for the following conditions to register as audible and visible alarms and to cause the generating sets main circuit breaker to open immediately and the generating set to immediately shutdown:

Emergency stop push-button: Pressed.

Generating set: Over voltage.

Generating set protection: Activated.

Generating set: Over current.

Engine: Overspeed.

Engine oil pressure: Low.

Jacket water temperature: High.

Automatic synchronising

Provide synchronising modules which automatically synchronise each incoming alternator supply frequency and phase angle to the live busbars, by the same manufacturer of generator.

6.3.05 Control panels

General

Provide control panels, switchgear and controlgear assemblies which accommodate equipment operating in parallel and stabilise load sharing between each generating set at all load steps. Include reverse power interlock.

Engine local control board

Provide digital microprocessor control with the following:

Key operated local engine start/stop control.

Controls for auto/off/manual/load test.

Emergency manual shutdown.

Speed indicator, kW meter, frequency meter, ammeter, kvar meter, power factor meter, and hours run meter.

Indicator showing generating set under local control.

Oil pressure indicator.

Coolant temperature indicator.

Undervoltage protection: Adjustable down to 90% rated voltage with time delay 0 10s.

Under frequency protection with two stages.

First stage: Adjustable 47-50Hz with time delay 0 10s.

Second stage: Adjustable down to 40Hz and with instantaneous trip.

Automatic voltage regulator consisting of the following:

Switch to select manual or automatic voltage control.

Solid-state type automatic voltage regulator.

Under and overvoltage sensing.

Power transducers.

Over and underspeed sensors.

6.3.06 Batteries and chargers

General

Provide separate batteries and charger systems for

engine start; and

control and alarm functions.

Standards

Engine start batteries: To TCN 20_1984.

Battery chargers: To TCN 20_1984.

Control and alarm batteries: To TCN 20_1984.

Control and alarm batteries

Location: Segregate battery and charger equipment from generator control equipment.

Capacity: Sufficient to supply full generating set control, monitoring and alarm functions for a period of 48 hours, and then operate circuit breaker and transfer devices for 10 consecutive open-trip-close cycles with mains supply off and at minimum ambient temperature.

Chargers - control and alarm batteries

Alarm outputs: Provide the following local audible and visual alarms together with facilities for extending them via a common alarm output to a remote location:

Mains off.

Over voltage.

Over current.

Low battery voltage.

Insufficient charge rate.

6.3.07 Starting

Electric starting

General: Provide starter motors, batteries and chargers, and associated control equipment to automatically start each engine.

Wiring: Wire starter motors so that starter motor solenoid contacts are on the active side and field windings are at earth potential when the motor is de-energised. Provide an interlock, connected directly to the engine, to prevent the starter motor operating when the engine is running.

Starting interlock: Provide a starting lock out system which prevents further starting attempts after 3 successive unsuccessful attempts.

Starting batteries

Location: Locate in proprietary battery holders attached to the generating set, or on purpose-built stands next to the set and constructed of timber or other corrosion resistant material. Isolate batteries from vibration.

Covers: Provide a high-impact resistant transparent cover for each battery.

Capacity: Sufficient to crank the engine for 3 successive attempted starts, repeated at 5min intervals.

Isolator: Provide a lockable isolator to prevent accidental starting.

Starting batteries chargers

Mains power: Connect chargers to the generating set auxiliary supply so that mains power is maintained when the generator system is in operation.

Alarm outputs: Provide the following local audible and visual alarms together with facilities for extending them via a common alarm output to a remote location:

Mains off.

Over voltage.

Over current.

Low battery voltage.

Insufficient charge rate.

6.3.08 Marking

Rating plates

Temperature-rise limits: If temperature-rise limits are achieved by de-rating an oversized generator, state the de-rated value.

Alternator mass: State alternator mass.

Thermistor detector identification and warning plates

Thermistors: Provide details of thermistor type classification and reference temperature.

Warning: Provide a warning engraved in 4mm high lettering as follows:

WARNING - Do not apply more than 2.5V across the protection thermistor devices.

Anti-condensation heater identification and warning: Locate next to heater terminals. State the number, voltage and power rating of the heaters, and the following separate warning engraved in red letters on a white background:

WARNING - Anti-condensation heater. Circuit is live when the set is off.

Auxiliary wiring

Provide ferrules to wiring ends identifying each conductor.

Engine direction of rotation

General: If driving shafts or associated rotating parts are accessible, clearly and permanently mark the direction of rotation on an adjacent fixed surface.

Rotation identification: Provide a label within the supply cable terminal box identifying the relationship between the direction of rotation and the marking of terminals.

Charger enclosure markings

General: Provide enclosure with

main nameplate engraved in 10mm high lettering;

minor nameplates engraved in 4mm high lettering to interior and exterior components;

manufacturers rating plates; and

markings to AS4044.

Plate material: Stainless steel.

6.4 INSTALLATION

6.4.01 General

Mounting

The engine and alternator units are to be mounted in the manufacturers factory on a common structural steel frame to support the generating set assembly and the engine local control board.

Plinths

Provide reinforced concrete plinths for floor mounted equipment, sized to suit equipment footprints.

Resilient mounts

Provide at least 6 resilient mounting blocks between the frame and the plinth.

Coupling

Directly couple the engine and generator shafts with a self-aligning type coupling, capable of transmitting the engine maximum output torque under operating conditions, including starting and overload.

Signs

Warning: Provide the following on each side of each generating set:

WARNING: This set may start at any time without notice.

Lettering: 50mm high, red on white background.

Drip trays

General: Provide removable drip trays under those parts of the assembly where fuel or lubricant leakage may occur. Provide overflow outlet pipes taken to a point where a receptacle can be fitted under the pipe outlet.

Capacity: At least 1.5 times the oil capacity of the engine sump.

Drain the drip trays via 32mm copper drain pipes, through to the basement with a shutoff valve to allow the oil to be dropped into an oil drum there if required

Emergency stop push-buttons

Provide 2 push-buttons for the generating set. Locate one on each side or locate one of the push-buttons in the engine local control board.

Type: 40mm diameter red, palm operated type mounted in a metal wall box fixed to a free standing U channel pedestal. Wire to disconnect the generator and immediately shut down the engine when the controls are in the automatic or manual mode.

Fuel connections

Fuel piping and associated auxiliary equipment

Stop valves: Provide stop valves on the inlet to, and outlets from, the daily service tank.

6.4.02 Acoustic enclosures

General

Provide weatherproof acoustic enclosures to surround the generating set, including inlet and outlet sound attenuators by the same manufacturer of generator.

Sound pressure level limit

85dB(A) at 12 locations 1m from the enclosure exterior surface, at 1.5m above floor or roof levels, measured with the generating set operating at constant maximum rated full load output, with doors closed and service penetrations sealed.

Dimensions

Size enclosures to accommodate diesel engine inlet and outlet attenuators and permit an unobstructed walkway at least 600mm wide between the generating set and internal face of the enclosure.

Plinths

Provide reinforced concrete plinths sized to suit footprints of acoustic enclosures, to serve as the walkway surface.

Doors

Provide doors of same material as the enclosure. Provide door stays to each door.

Ventilation

Provide ventilation to the enclosure so that

With generating set running at full rated output the enclosure temperature-rise does not exceed 10oC Hazardous concentrations of toxic or explosive fumes and gases are prevented.

Lights

Provide internal lighting to 300 lux.

Signs

Fit the following signs to single doors, and the left hand leafs of double doors:

Wear hearing conservation protection, to AS1319.

WARNING: This machine may start at any time without notice, in red lettering on white background.

6.4.03 Engine cooling

General

General: Provide a cooling system consisting of radiators, fans and pumps.

Cooling air ductwork: Connect the cooling air outlet of generator to generator room cooling air outlet.

Provide pressore drop calculation on actual outlet duct.

6.4.04 Engine air intake

General

Provide dry type air intake filters of sufficient capacity to permit continuous engine operation for 1,000 hours before filter servicing becomes necessary.

Provide dirty filter indicators.

6.4.05 Exhaust system

General

General: Provide exhaust piping from the engine complete with silencers, piping, ductwork, supports and expansion devices.

Silencer: Residential type.

Exhaust piping: Grade 321 Stainless steel.

Diameter: Match engine exhaust manifold connection.

Connections: Provide flanged connections to silencers and pipe interconnections.

Vibration isolation: Provide a stainless steel flexible connection to the engine.

Expansion joints: Provide stainless steel expansion joints in riser.

Ensure that exhaust system matches engine configuration, and that exhaust manifolds combine to a single silencer if necessary to meet noise requirements.Weatherproofing

Provide weatherproof flashing, sleeves and acoustic seals where the exhaust system penetrates the roof or external walls.Exhaust drainage

Grade the exhaust line away from the engine to drainage pockets, or connect to a suitable valved drainage outlet.

Lagging

General: Lag internal exhaust piping and ductwork with calcium silicate insulation sheathed with zinc-coated steel sheet.

Lagging: Lag with 200mm rockwool plus 10mm calcium silicate board, sealed with fire rated putty.

6.5 COMPLETION

6.5.01 General

6.5.02 Spares

Provide the recommended spare parts for the equipment as follows:Start-up, commissioning and one years operating spares to be purchased with the base equipment.Provide the recommended spare parts list & costs for the equipment as follows:2 years operational spares.The spare parts lists shall give all manufacturers part numbers in addition to any numbers used by the Supplier.

All spare parts furnished by the Supplier shall be wrapped and packaged to preserve original as-new condition under conditions of storage. All spare parts shall be properly tagged and coded so that later identification as to their intended equipment usage will be facilitated. All items supplied shall be packaged separately and clearly marked as Spare Parts and shipped with the equipment in accordance with the instructions from Purchaser. Packing lists shall be furnished complete and in detail.

6.5.03 Tools

A Tool box with all necessary tools for daily check, routine maintenance shall be supplied. A tool list also need to be submitted for approval.

6.5.04 Completion test

Acceptance tests generally

Follow requirements of manufacturer.

Check tightness of connections and securing devices.

Verify correctness of operation of protection devices and systems including sensor settings. Simulate actual conditions as far as possible, in order to test responses to faults imposed.

Cold start with the engine having been at rest for the previous 24 hours, timed from receipt of mains failure signal to acceptance of full rated load in 3 load steps to within the limits of output voltage and frequency.

Continuous operational trial consisting of:

4 hours at 100% rated power.

30 min at 75% rated power.

30 min at 50% rated power.

Record fuel consumption for each step of the continuous trial.

Sample engine oil from engine sump before and after tests. Perform laboratory analysis and submit a report on each oil sample.

Continuous operational trial: During the trial, measure the following at maximum intervals of 30 minutes:

Generator kW and kvar output.

Generator output voltage.

Generator output current.

Generator output frequency.

Power factor.

Oil pressure and water temperature.

Electrical power requirements of continuously running electric motor driven ancillaries.

Each battery charger current and voltage readings.

Noise level.

Temporary test loads

Provide 100% resistive load banks for load testing.

Final tests

Submit reports from manufacturers or suppliers verifying the performance of safety and control functions of each system.

6.5.05 Maintenance

General

Allow for servicing during the first year of service or up to 1000 hours, whichever occurs first, by the manufacturer.

Call out

Respond to call outs for breakdowns or other faults requiring corrective maintenance. Attend on site within 24 hours of notification. Rectify faults and replace faulty materials and equipment

Consumables

Replace all oil and air filters after acceptance tests.

Provide all consumables (filters, oil, fuses, lamps etc) for the defect liability period.

Replace all oil and air filters at the conclusion of the defects liability period.