WASTE WATER TREATMENT PLANT

WASTE WATER TREATMENT PLANT ELECTRICAL: GENERAL SPECIFICATION Contents List Section Description 1.0 2.0 Not Used Materials and Equipment 2.0 Materials and Equipment 2.1 Panel Construction 2.1.1 The layout of components within an enclosure or compartment shall allow clear access to all components. Protruding equipment or racks shall not obscure access. Components shall be secured in such a way that the method of fixing allows for their easy replacement, eg tapped holes, welded nuts, hank bushes, etc. 2.1.2 All components and conductors shall be co-ordinated with the short circuit protective device such that flow of fault current will cause no damage, and subsequent operation of the equipment is unaffected. 2.1.3 All access doors shall be padlocked with a 6mm diameter shackle to prevent unauthorised access. The padlock type shall be approved by CPA. No tools shall be required for access after removal of the padlock. 2.1.4 All terminals which remain live, or may become live during functional testing, when the compartment door is open shall be shrouded to a minimum of IP2X. 2.1.5 The degree of ingress protection for enclosures shall be as follows: (i) Switchrooms or Control rooms housing electrical equipment only: IP 42. (ii) Indoor Plant areas: IP 54. (iii) Outdoor: IP 65 (except motors). 2.1.6 The maximum and minimum heights above Finished Floor Level for various types of components shall be as follows: Component Max Min Operating handles or devices - 2000mm 250mm Indicating devices - 2100mm 350mm 2.1.7 Doors shall be arranged such that they give the maximum permissible opening without damage to or affect the operation of equipment on adjacent compartments, the opening shall be at least 90°. Doors shall be prevented from unrestrained opening by either an integral facility in the hinge/door design or by a restrainer. Restrainers utilising cable and crimped electrical lugs will not be accepted. 2.1.8 Where key operated equipment is provided, other than safety interlocks, not less than two keys of each type shall be forwarded to the Project Manager at the time of despatch of the switchboard. 2.1.9 All anti-condensation heaters shall be fed from a 110V ac buswired supply via a fuse terminal/neutral link located in the common control supply compartment and sub-fused to protect each heater and thermostat. Final connections to heater elements shall be adequately rated for the temperature rise. 2.2 Isolation of Electrical Equipment 2.2.1 All compartments, except those containing terminals only shall include an associated door mounted isolator which shall isolate all incoming supplies above 25V ac/60V dc, except for "function test" and Instrumentation Panel lighting circuits. Where double doors are provided they shall be arranged such that the isolator cannot be operated with either door open. 2.2.2 Except for instrumentation panel 110V incoming supply, the handle of every isolator shall be interlocked with its compartment door, to ensure that the door cannot be opened or closed with the isolator in the 'ON' position. Care shall be taken to ensure that any isolator operating extension shaft is adequately supported to avoid alignment problems. The maximum unsupported length shall be 150mm. 2.2.3 All isolators shall be capable of making onto a fault and breaking the design current. 2.2.4 Every isolator shall be equipped with facilities to enable it to be padlocked in the 'OFF' position only, with the compartment door open or closed. Padlocking facilities shall be suitable for a padlock shackle having dimensions of 5mm diameter x 30mm. 2.3 Control and Instrumentation 2.3.1 All control circuits and instrumentation supplies shall have an operating voltage matching existing at site. Signal voltages between separate compartments within panels where isolation for maintenance is not possible, shall be no greater than 24V dc. 2.3.2 All devices that require resetting shall be capable of being manually reset with the compartment door closed. 2.3.3 Indicating lamps shall be transformer operated 220 Volts primary. All lamps shall be over-rated by approximately 15% of their normal service voltage. 2.3.4 The following colours shall be used for equipment push buttons and indicating lamps: Stop Push Button - Red Start Push Button - Green Reset Push Button - Black Functional Test Button - Yellow ‘Motor Running’ Indicator - Red ‘Motor Stopped’ Indicator - Green ‘Motor Tripped’ Indicator - Amber ‘Starter available’ Indicator - White 2.3.5 All indicating instruments/meters shall be selected from a single manufacturers range and be flush mounting with back connections shrouded to IP 2X. Instruments shall have non-reflecting glass, a suitably ranged scale with black markings on a white background and front-mounted zero adjustment. The minimum accuracy shall be ±1.5% of full scale deflection. 2.3.6 Control circuits shall be designed to accept the incorporation of emergency stop pushbuttons, operable in any mode of control. Where motors are closely grouped and form part of a single process stream, they may be controlled via a single emergency stop pushbutton. Emergency stop pushbuttons shall be normally closed stayput type with a mushroom head twist to release. Removal of the emergency stop signal shall require manual resetting at the control panel. 2.4 Identification and Electrical Safety Labelling 2.4.1 All covers, doors or shrouds which if removed uncover unisolated electrical equipment, shall be labelled with the electricity warning symbol. 2.4.2 All doors, removable covers and cable compartment rear entry point which give access to apparatus or equipment shall be labelled stating the designation of the items enclosed and tag number. External labels shall be fixed by means of screws or rivets. Proprietary danger or caution labels may be self-adhesive. Labels shall be engraved in English/Arabic 2.4.3 All components shall be identified in accordance with schematic diagrams. Components may be identified on one common label/drawing corresponding to the internal layout. Component identification labels shall not be affixed to components or removable items. Labels shall be visible and shall not be obscured by cables, equipment, etc. Labels shall be provided to indicate the schematic reference number and rating of all fuses and links. 2.4.4 On existing sites where drives restart on release of the emergency stop pushbutton, each button shall be labelled with the following information, having white text on a blue background. OPERATIONAL INFORMATION i Revised emergency stopping circuit. Reset at the starter. 2.4.5 Where Intrinsically Safe equipment is installed within a compartment, then the front cover of that compartment shall be labelled as follows: Caution Compartment Contains Intrinsically Safe Equipment The label shall have white lettering with a blue background. 2.5 Internal Wiring and Termination 2.5.1 All wiring shall be identified to correspond to the schematic diagram by means of markers, which shall be the correct size for the wire, and shall read from the terminal outwards. No wire number shall be repeated within a panel compartment. All outgoing wiring terminals shall be uniquely numbered. To allow easy identification of the wire markers there shall be a minimum clear run of 35mm of wiring leaving any terminal before it is obstructed by a component, the top/sides/bottom of the compartment or when entering cable trunking/looming. This clear run shall be increased as necessary where cable bunching restricts access/identification of wire markers. 2.5.2 Power cables shall have a minimum size of 2.5mm. Control cables excluding instrument loops shall have a minimum size of 1.0mm. 2.5.3 Wiring within compartments shall, where practicable, be run in plastic cable trunking. Where it is necessary to use wiring looms, they shall contain no more than 20 wires. 2.5.4 Terminals shall be grouped together and identified in a logical manner in relation to the outgoing cabling. Terminals isolated at different points shall be suitably segregated in their respective groups and different types or voltages shall be segregated by large barriers. 2.5.5 External cabling to circuit breakers, fused switches, isolators, fuse holders or MCCBs shall connect directly to these components. All other circuits shall be provided with interposing terminals. Terminals shall be so positioned to ensure that external cable conductors can be installed taking due account of the minimum bending radius of that cable or core and that there are no obstructions to external cable entry. Every wire except for earth loops, shall be individually terminated with a correctly crimped lug or pin and not more than two wires shall be connected to any one terminal connection. There shall be individual connections for each external cable core. Terminals shall be easily accessible for test purposes. Removal and replacement of conductors shall be possible without disturbing other conductors. 2.5.6 Terminals and wiring for intrinsically safe circuits shall be coloured blue. 2.6 Hazardous Areas Where equipment operates in a potentially explosive atmosphere, it shall be suitable for Zone 1 use together with the Gas Group and Temperature Classifications detailed in the Contract Specific Requirements. Such equipment shall be in accordance with EN 50014 and shall be EEx certified by an appropriate EC certifying authority. Standard Specification: Electrical - General PAGE 1 of NUMPAGES 7 ED 5/1/88 SECTION 1 © CPA Water Technology Limited 1997 Version 1.0 Page PAGE 1 of PAGEREF SEC1 \* MERGEFORMAT 1 (Rev 5) ED 5/1/88 SECTION 4 © CPA Water Technology Limited 1997 Version 1.0 Page PAGE 3 of PAGEREF SEC4 \* MERGEFORMAT 5 (Rev 5)