Correlaci´ on de modelos t´ ermicos matem´ aticos

1 GENERAL

GENERAL INTRODUCTION

This Specification describes the requirements for 400 V motor control centres (MCC). The motor control centres shall be designed and provided in accordance with this Specification and the electrical schematic diagram.

The scope of supply includes the design, manufacture, installation, testing and commisioning of the 400 V motor control centres as described above.

Equipment unloading and storage at the Job Site.

All equipment shall be designed, manufactured and tested in accordance with the applicable IEC 439-1, EN 61439-1 form-3b, or form as shown as drawings, IEC 947-4, IEC 801 standards and shall meet the requirements of DEWA.

Dedicated MCC’s as mentioned on drawings for pumps shall be form-2, type-2 with incomer MCCB (N/A) / Isolator.

All MCC’s shall be weather proof to IP-54.

Subject to compliance with the requirements of the contract documents, acceptable manufacturer of all materials specified in this section of types and sizes required, whose products have been in satisfactory use under similar servicer conditions for not less than five years. ambient temperature range of 0°C to 65°C.

The normal operating altitude shall be less than 1000 m above sea level.

2 Specifications

The MCC technical requirements shall be in accordance with the data sheets, single line diagrams and schematics

The motor control centres shall be suitable for operation on 400 V, 3-phase, 3 wire, 50 Hz, front mounted, installed on steel channel sills.

All power bus bars as well as all other current carrying parts shall be of copper.

The main horizontal bus bars shall be insulated and isolated, and rated as indicated in single line diagrams, and shall run continuously the entire length of the control centre, except when it may be necessary to cut and provide splice plates as between shipping sections. The main bus shall be housed in an isolated compartment. Vertical bus bars extending the full height of each section shall be provided. The vertical bus shall be insulated with flame-retardant material. All

buses shall be braced for 50,000 symmetrical amps RMS short circuit current. All bus assemblies shall be supported by steel framework with insulators of moulded glass polyester. Provision shall be made to extend MCC on either side.

Motor control centres shall have a continuous horizontal copper earthing bus installed in the bottom of the MCC. It shall extend through each section of the control centre and shall be provided with compression lugs at each end. Vertical ground bus extending down each vertical section shall also be provided.

Incoming sections shall have top entry. Space shall be adequate to accommodate incoming bus ducts supplied by others. MCC Supplier shall coordinate with the main contractor regarding details of bus ducts.

Outgoing power and control wiring shall be from top.

Each control centre shall be provided with a laminated phenolic nameplate, white outer layers with black centre layer, 75 mm x 200 mm, with bevelled edges.

Lettering shall be engraved into the phenolic to produce black letters on a white background. The MCC number shall be in 25 mm high letters and numerals. All other lettering shall be a minimum of 10 mm high. Tabreed equipment and purchase number shall be engraved on the nameplate. The nameplates shall be firmly fixed to the MCC’s.

Vertical Sections

- Each motor control centre shall consist of one or more rigid free standing vertical section(s) bolted together to form a unit assembly.

- Sections shall be suitable for mounting starters in front of the section.

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- Vertical sections shall be front connected and be capable of being wired from the front without removing any units. Adequate vertical wiring space accessible from the front shall be provided in a separate vertical isolated wireway, with covers.

- - Openings, covered by removable gasketted plates, shall be provided in ends of vertical sections to allow for future addition of vertical sections at either end. Removable plates shall also be used to cover the top and any unused space on the front and back of the control centres. Where called for in specific requirements, space shall be provided for installation of future units. This space shall be complete with bus, unit supports and isolating barriers.

Unit Compartments

Each control unit shall be designed for mounting within a vertical section in such a manner that each unit will be completely enclosed and isolated from all other units. Adequate space shall be provided for entry of wiring from the vertical wiring trough. Control units shall be “plug in” type construction, equipped with self-aligning stabs of a type that will increase contact pressure on short circuits.

Control units shall be capable of independently and satisfactorily clearing a fault on the load side of the starter with 42,000 symmetrical amperes available at the

Each unit compartment shall be provided with an individual front door. Starters and feeder unit doors shall be interlocked mechanically with the unit disconnect device to prevent unintentional opening of the door with power on and unintentional application of power while the door is open.

Means shall be provided for releasing the interlock for intentional application of power, if desired, while the door is open. Padlocking arrangements shall permit locking of the disconnect device in the OFF position with a maximum of 3 padlocks with the door closed or open.

Starter disconnect devices shall be operable from outside the enclosure and shall show position of disconnect device whether compartment door is opened or closed.

Similar nameplates showing unit location I.D. shall be installed at left top corner of front door of each unit.

Special tools and equipment shall be provided for operation and maintenance purposes.

STARTERS,DISCONNECT AND ACESSORIES

Motor starters shall be in accordance with this specification. The maximum starting currents for motors shall be:

- Less then 10 hp –5 times full load current - 10 hp to 50 hp -2 times full load current

- 50 hp and above -1.5 times full load current The stationary equipment shall be as follows:

Motors up to 10 hp will be connected Across-The-Line with over current protection Motors 10 hp and above shall be controlled with motor starters of a soft start design.

Provide moulded case circuit breakers (MCCB) for feeders with current limiting protection as indicated on single line diagrams. The rating of the MCCB’s shall be in accordance with the load indicated on the single line diagrams with a minimum of 65kA interrupting capacity.

ACROSS-THE-LINE STARTING

Controllers shall be of circuit breaker combination type with full voltage magnetic starters for across-the-line starting. Full protection of each phase shall be provided in starters by means of electronic overloads.

Undervoltage protection shall be provided by the starter coil to disengage on 65%

of rated voltage unless otherwise noted.

ELECTRONIC OVERLOAD RELAY

Vendor shall provide an electronic overload relay for connecting the starter.

The overload relay shall have a current adjustment range of 5:1 or greater.

The overload relay shall have +/- 2.5% setting accuracy.

The overload relay can be converted from manual to automatic reset.

The overload relay trips in two seconds or less under phase loss conditions when applied to fully loaded motor.

The overload relay provides a visible trip indicator.

The overload relay provides led status indication.

The trip indication LED flashed in a pattern that indicates the trip cause.

The overload relay provides 1 N.C. auxiliary contact.

The overload relay provides a test trip function that when operated trips both the N.C. contacts and the N.O. triac outputs.

The overload relay has trip free construction

The overload relay is ambient temperature compensated

The overload relay has user selectable 10, 15, 20 or 30 tripping classes The overload relay has user selectable jam/stall protection.

The overload relay has user selectable ground fault protection.

The overload relay is compatible with a hand-held or panel-mounted interface device that provides a two-line Bakelite LCD and start, stop and reset control functions.

The overload relay can communicate on an open communications bus.

The overload relay provides the following information on a communication network.

- Average Current

- Percent Phase Imbalance - Percent Thermal Capacity Used - Trip Cause

- Full load Current Setting - Output Triac Status

The overload relay provides two triac outputs that enable the overload to control two starter coils.

The overload relay provides the following control functions on a communication network.

- Start - Stop - Reset

Variable Frequency Drives

Vendor shall provide variable frequency drives (VFD) for applications that require varying the speed of squirrel cage motors as indicated on single line diagrams.

The VFD shall be as detailed in Section 5.

Power Correction Capacitors Refer Section 7 for details.

3 INSPECTIONS AND FACTORY TESTS

MCC’s shall be inspected at each stage of manufacture in accordance with the Vendor’s quality assurance program and shall be completely assembled in the works. All deficiencies shall be corrected before shipment. Seller shall advise the Consultant 5 (five) working days before completion and before testing commences to Consultant, if required, to make arrangements to witness the inspection(s) and tests.

MCC’s shall be tested in the manufacturer’s works in accordance with the referenced standards. Tests to include:

- Routine functional tests.

- Insulation (Megger) and hi-pot of wiring.

SECTION 7