GENERAL AND DESIGN REQUIREMENT
1. Process heat trace control panels :
1. Main incoming isolator.
2. Power distribution panel board.
3. Temperature controllers (by PENTAIR).
4. Contactors or relays.
5. “POWER ON” indicating light (red).
6. Terminal blocks for outgoing cables.
7. Anti-condensation heater (if required).
1.1 Control Panels
1.1.1 Each control panel shall be housed in a free standing, weather proof (IP55), corrosion resistant enclosure. The panel housing shall be completely enclosed with full height lockable hinged doors on the front and shall have a steel back panel for mounting of equipment.
1.1.2 The panel enclosure shall be provided with thermostatically controlled anti-condensation heaters and shall be complete with all required components including a main isolator, power distribution panel-board, contactors, relays, temperature controllers, control switches, indicating lights, terminal blocks, ground bus, and all power and control wiring internal to the panel. Provisions shall be made for looking out of individual heater circuits for maintenance and testing.
1.1.3 Branch circuit breakers shall be miniature circuit breakers ( MCB ), single pole.
1.1.4 2 pole branch circuit breakers shall be used for breakers supplying heater circuits in hazardous areas.
1.1.5 Ground fault equipment protection with a 30 mA trip is required for each circuit breaker supplying heater circuits in hazardous areas.
1.1.6 All contacts specified for initiation of remote circuit failure and over temperature alarms shall be wired together to provide two single remote alarm functions. The (failure and temperature control) alarm contacts shall be wired each to a common set of terminals which shall be provided for external alarm wiring connections.
1.1.7 Terminal blocks shall be provided for terminating all power, control and instrument wires entering each control panel. Terminal blocks shall be rail mounted modular type with tubular screw pressure plate wire connections.
1.1.8 Each utilized terminal point shall be permanently marked as identified on the electrical drawings. minimum of 20 percent spare terminal rail space shall be provided.
1.1.9 All shield drain wires for instrument cable shall be terminated on terminal blocks located adjacent to the cable conductor terminals. All shield terminals shall be connected to the control panel ground bus. shields shall be grounded at the control panel only.
1.1.10 A copper ground bus shall be installed at the bottom of each control panel assembly and shall be solidly bonded to the panel enclosure. The ground bus shall be minimum 70mm2 copper and shall extend across the entire width of the enclosure. The ground bus shall be provided with two main lugs ( one at each end ) for connection of 70mm2 copper cables to the plant grounding grid.
1.1.11 All instrument cable shields and all equipment ground wires entering the control panel shall be connected to the ground bus using bolt-on grounding lugs.
1.1.12 All major electrical components, control devices, instruments, and remote junction boxes shall be labelled in accordance with the drawings.
1.1.13 Nameplates shall be made of laminated phenolic with white letters engraved on a black background and lettering 5mm high minimum. Each nameplate shall be fastened with stainless steel screws. Attachment of nameplates shall not compromise the required enclosure classification.
1.1.14 Power distribution panel boards shall be provided with typed directories and all breakers shall be individually identified with engraved nameplates showing circuit numbers. Breaker nameplates shall have adhesive backing for attaching to panel-board.
1.1.15 A main nameplate shall be furnished on the front of each control panel. The main nameplate shall show panel number and description. Engraving for the main nameplate shall be with minimum 12mm high letters.
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