Section 13 — Electrical

Motor Control Centers 600 Volt Class

IPE Engineering Practice IPE-EP-13-6-2

Document number: IPE-EP-13-6-2 · Section: 13 — Electrical

SCOPE

• This Practice including the 600 Volt Class Motor Control Center Data Sheet (EP 13–6–2DS), covers the requirements for assemblies of 600 volt, 3 phase, 3 or 4 wire, 60 hertz, indoor NEMA 1 and outdoor NEMA 3R weather resistant motor control centers. The equipment shall be manufactured using best quality materials and workmanship and the latest state–of–the–art in technology. The equipment shall be complete in all respects and ready for operation.
• This Practice is appropriate for attachment to an inquiry or purchase document when accompanied by the referenced IPE Practice and completed Data Sheets.
• Any deviation from this Practice must be approved by the procedure described in EP 1–1–3.
• A revision bar indicates all changes made to this Revision.

2.0 REFERENCES

All applicable sections of the latest standards and codes listed below are a part of this Practice for design, construction, wiring and testing unless amended herein. It shall be the Manufacturer’s responsibility to become knowledgeable of the requirements of these Standards and Codes and any changes or alterations to the equipment to make it meet the requirements shall be at the expense of the Manufacturer.

STANDARDS AND PUBLICATIONS

3.0

3.1

3.2

3.3

3.4

3.5

3.6

4.0

5.0

5.1

5.1.1

DEFINITIONS

Contractor – Company or business that agrees to furnish materials or perform specified services at a specified price and/or rate to the Owner.

Inspector – A Inflection Point Engineering, LLC appointed engineer or inspector.

Manufacturer – The recipient of a direct or indirect purchase order for materials and/or equipment. In this context, a direct order is one issued to a Manufacturer by a Contractor or the Owner. An indirect order is one issued to a Manufacturer by a vendor (recipient of a direct order) for materials, fabricated components, or subassemblies.

Owner – Inflection Point Engineering, LLC.

Owner’s Engineer – A Inflection Point Engineering, LLC appointed engineer.

Purchaser – The party placing a direct purchase order. The Purchaser is the Owner’s designated representative.

SERVICE CONDITIONS

600 volt class motor control centers shall perform satisfactorily when operated indoors or outdoors in a sheltered–aisle housing, either intermittently or continuously in an atmosphere typical of petrochemical plants. The motor control centers shall be for use in a 104F maximum ambient, –15F minimum ambient and at an attitude of 3,300 feet or lower.

DESIGN, CONSTRUCTION AND MATERIALS

Basic Construction

General Requirements

• Enclosure
• Each assembly shall be metal–enclosed, free standing, dead–front, vertical steel structures containing power buses, combination starters, feeder breakers, metering, ground bus, control equipment and other specified devices.
• The vertical sections shall be a minimum of 20 inches wide, 15 inches deep, and maximum of 90 inches high and designed to prevent “heat build–up” in the upper spaces.
• Vermin and winged insect proof screens shall cover all openings.
• All hinged front doors shall be equipped with gaskets to exclude dust.
• Future Expansion: Provisions shall be made for the addition of future control center sections at both ends of the equipment with continuation of power buses, ground bus, enclosure, etc.
• Provisions for Handling, Storage and Field Erection
• Each “shipping section” of stationary structures shall be provided with removable lifting angles and/or plates suitable for crane hooks or slings as well as removable steel channel base plates or provisions that will permit using pipe rollers or dollies without damaging the steel frame of the equipment.
• Equipment shall be packed, crated, and rigidly braced to protect it from the weather and from damage during handling and outdoor storage.

• Space Heaters
• When specified on the Data Sheets, thermostat controlled electric space heaters shall be installed to prevent condensation of moisture in the motor control center.
• The rated voltage of these heaters shall be 240 volt AC, but they shall be operated on 120 volt AC. The heaters shall be sized to provide adequate heat at the lower voltage.
• All heaters within each assembly shall be controlled by one single circuit breaker located in the assembly. The entire circuit shall be wired to an accessible terminal block providing for a single connection of the external power source by the Purchaser.
• Provisions shall be made to energize the space heaters of each shipping section during storage at the jobsite. The electrical connection point shall be readily available without uncrating the equipment and shall be clearly identified with the specific electrical service required.
• Painting: Each assembly shall be cleaned, primed and painted with a minimum of two coats of paint. The final finish for indoor assemblies shall be ANSI No. 61 or No. 49 gray. The final finish for outdoor assemblies shall be ANSI No. 24 or No. 70 gray. The seller shall supply one quart of matching paint per assembly for field “touch–up” after installation. Paint shall be supplied in aerosol cans with non–CFC propellant and with appropriate MSDS sheets.
• All motor control centers shall be UL listed. Provide UL listing nameplate for vertical sections and for each unit.
• Outdoor Assemblies (Walk–In and Non–Walk–In)
• Motor control assemblies for outdoor installation shall be rated NEMA 3R and be weather and rodent proof, fully gasketed and equipped with lighting, convenience receptacles, and thermostatically controlled unit space heaters. In addition, the overall enclosure shall have thermostatically controlled heaters, adequate ventilation.
• Positive ventilation when specified shall be accomplished by a blower such that the temperature in the maintenance aisle will be no more than 5F higher than the outside temperature (95ºF). Blower suction shall be taken near the top of the assembly wall. A thermostat shall be provided in series with a manual on–off–auto switch for fan control.
• Walk–in enclosure aisle width shall permit room for maintenance and testing. Entry doors with provision for locking with padlocks shall be provided on each end of the assembly, unless otherwise noted. Doors must permit opening from the inside even when locked. Each vertical section of non–walk–in enclosures shall have a full height, hinged outer front door.
• The undersurfaces of the assembly shall have a heavy, rubberized sealing material, or similar approved anti–corrosion coating.
• Exterior hardware shall be corrosion resistant material preferably stainless steel.
• Walk in enclosures without forced ventilation shall be equipped with screened/filtered and weather proof ventilators and/or louvers for the walk–in area.
• The outdoor modules/units shall be designed to have a wind stability greater than 75 mph (130 mph maximum).

• Buses
• Power Buses
• All power buses shall be copper with tin–plated joints. Silver is not an acceptable plating material.
• Main buses shall be completely isolated at the front, top, rear and bottom. All busbar phase sequencing shall be as per ANSI standard; i.e. 1, 2, and 3 arranged from front to back, top to bottom, left to right, as viewed from the front of the control center.
• Vertical buses shall be insulated and isolated so that with the unit doors open and units removed, the only visible bus bar will be where the unit stabs make contact.
• Spacing between 480 volt bare live parts shall be one inch minimum through air and two inches over a surface between buses of opposite polarity and between bare live parts and ground.
• Minimum ampere ratings shall be 600 amperes for mains and 300 amperes for vertical. Required ratings will be shown on the Data Sheets.
• Track–resistant individual bus supports having a high impact strength shall be used for each bus so as to provide maximum creepage and air clearance distances.
• The minimum bus bracing shall be 42000 ampere RMS symmetrical, unless specified otherwise on the Data Sheet.
• All unused openings on the insulated vertical bus shall be provided with shutters or fitted inserts to cover stab openings when units are withdrawn. Bus insulation shall be removed on all spaces identified as a specific size future starter/circuit breaker to allow installation without having to de–energize the MCC to remove power bus insulation.
• Horizontal buses shall have a minimum of 2 bolts per joint.
• Neutral Bus: When specified on the Data Sheet, a full capacity copper neutral bus with tin– plated joints shall be supplied.
• Ground Bus: A continuous 1/4–inch by 2–inch (minimum) copper ground bus shall be run in the horizontal wireway and provided with a 2/0 AWG solderless cable connector at each end.
• Wiring and Wireways
• Wiring
• Wiring shall be NEMA Class I, Type B.
• The minimum wire size for power circuits shall be #12 AWG. The minimum wire size for control circuits shall be #14 AWG.
• Internal wiring of combination starters shall be suitable for the maximum horsepower rating of the starter. The minimum internal wiring and load side cable lugs shall be as shown in Table 1.
• All control and power wiring shall be stranded copper wire with XHHW, XHHW–2, SIS or MTW insulation rated 600 volts or higher to ground.

• All wiring shall be neatly bundled, secured and protected against contact with any sharp metal edges. There shall be no spliced conductors or repaired insulation.
• Extra flexible cable shall be used between stationary and hinged panels.
• When separate compartments are used for “incoming feeders”, they shall be arranged as follows: Cable lugs shall be installed at the top of the compartment for bottom entrance cables and at the bottom of the compartment for top entrance cables, leaving the maximum space for NEC allowable bending and “make–up” of the incoming feeder cables by field installers.
• When crimp type terminal lugs are used they shall be insulated sleeve, spade tongue type (except ring tongue type on all CT circuits).
• Terminal blocks shall be suitable for holding spade and ring type lugs. Blocks shall be rated as a minimum, 20 ampere, 600 volt. As a minimum, twenty percent spare terminal spaces shall be provided. All spare unused terminal spaces shall have screws inserted.
• Each internal interconnecting wire shall be identified at each end with a plastic sleeve type, or shrink tubing wire identification system. Tape wire marks are not acceptable. Tabular wiring diagrams and wire marks are not acceptable. A destination address type system is preferred. Wiring diagrams as well as wire marks, device and terminal strip identification system to be used shall require approval of the Owner.
• Wireways
• Each vertical section shall have a minimum 4–inch wide vertical wiring space between the units and side sheet for unit wiring and shall be provided with a tightly secured, hinged access door of formed sheet metal.
• Each section shall be provided with horizontal wiring space at the top which shall line up with adjacent sections to form a continuous wiring raceway the entire length of the motor control center.
• Both horizontal and vertical wireways shall be completely enclosed and isolated from exposure to live parts.
• Equipment compartments, bus compartments, cable compartments and wireways shall be completely isolated from each other by means of steel barriers.
• Circuit Breaker and Combination Starter Units
• Control Center Units
• Units shall be of the draw–out type. Plug–in connections shall be made by self–aligning, plated stab type plug–in fingers designed to tighten onto the vertical bus during high currents. Stab plating and material shall be compatible with the bus material and plating.
• Access to the operational or spare units shall be provided by a separate hinged door, attached either to the section or to the unit. Any unused space that is not suitable for the addition of “plug–in units” shall be provided with a plain bolted sheet metal cover.

• Each compartment unit door shall be mechanically interlocked such that the door cannot be opened unintentionally when the external disconnect operator is in the “ON” position, and so the external disconnect operator cannot be turned to the “ON” position unintentionally when the door is open. A defeater means shall be furnished to permit trained personnel to by–pass the mechanical interlocks.
• Removal of the unit shall require that the door be open and shall not leave the bus so exposed that accidental contact with it is possible.
• Circuit breaker operating handle positions shall indicate “ON”, “TRIPPED” and “OFF” with the door closed and shall have provisions for padlocking with at least three padlocks in the “OFF” position with the door closed.
• Auxiliary devices such as control transformers, relays, current transformers, meters, etc., as specified on the Data Sheet, shall be installed in the same space unit as the starter, even though a larger space unit may be required.
• Each control center unit shall have a permanent door–mounted nameplate. Nameplates shall be laminated plastic, with black lettering on a white background. Nameplate data will be furnished on the Data Sheet.
• All pilot devices mounted in the motor control centers, such as push buttons, selector switches, pilot lights, and other such items shall be of the single–unit heavy–duty type, oil tight, meeting NEMA Std ICS 2–216 as a minimum, and be UL listed.
• All pilot/indicating lights shall be of the type specified on the Data Sheet.
• All control components shall be NEMA rated.
• Combination Motor (Starters) Controllers
• All motor starters shall be 3 poles, 600 volt, UL Listed combination motor starters (for full voltage across the line starting).
• Combination motor starters shall be suitable for use on systems with 42,000 RMS symmetrical fault current ampere available and be UL Listed to interrupt/withstand this available ampere. The requirement for higher AIC shall be indicated on the Data Sheet.
• The minimum size starter shall be NEMA Size 1.
• Contactor coils and relay coils shall be rated 110 volts AC.
• Control Transformers
• A 480/120 volt control transformer shall be sized, as a minimum, for twice the normal VA rating of the contactor and auxiliary devices furnished for each starter.
• Control transformers shall have one secondary leg fused, and the other secondary leg grounded. Connection to both secondary legs shall be provided at the control terminal strip.
• All control transformers shall have fused primaries.
• Overload Relays

• Each starter shall have three (3) ambient temperature compensated overload relays with door mounted external manual reset push button, or as specified on the Data Sheets.
• Overload relays shall be adjustable, with a minimum adjustment range of 90 to 110 percent of the heater rating.
• Overload relays with heater elements shall be sized for 115% of motor full load current for

1.0 service factor motors and 125% for 1.15 service factor motors. Motor full load currents and service factors will be supplied on the Data Sheet, or other purchase documents/drawings.

• Combination motor starter main disconnect and fault clearing device shall be provided as specified below and on EP 13–6–2 DS.
• Fused Switch
• The switch shall be a three pole gang operated, non–load break, quick make/quick break switch. Fuses shall be sized for fault protection only with motor overload protection provided via separate thermal overload devices.
• When a fused switch is provided, a local “run off” maintained position switch shall be provided to shutoff the attached motor load at the starter location. The run position shall not start the motor, but will enable the Owner’s remote start.
• Molded case circuit breaker; magnetic only motor circuit protector (MCP)
• The MCP shall have an adjustable magnetic trip unit properly sized to meet the NEC requirement of a maximum setting of 13 times motor full load amps and be designed to avoid nuisance tripping from motor starting inrush current.
• The minimum frame size shall be 100 ampere.
• Molded case circuit breaker--thermal magnetic
• The breaker shall have an adjustable instantaneous (magnetic) element. The thermal and instantaneous (magnetic) function shall be selected or adjustable to limits allowed by the NEC and have suitable time current characteristics to avoid nuisance tripping for motor starting inrush currents.
• Minimum frame size shall be 100 ampere.
• Electronic trip (solid state) molded case circuit breaker.
• The breaker shall be a non–drawout breaker with adjustable long time, short time and instantaneous functions.
• The breaker shall have interchangeable breaker ampere rating plugs.
• Minimum frame size shall be 100 ampere.
• Additional control and pilot devices required will be specified on the Data Sheet and/or drawings.
• All motor starters shall be supplied with a front door/panel “red” light to indicate motor running, unless specified otherwise on the Data Sheet.
• Combination motor starters shall be provided with two spare N.O. and two spare N.C. auxiliary contacts rated 10 ampere, 120 volts AC. Additional auxiliary contact requirements shall be indicated on the Data Sheet.
• When specified, a motor starter shall be equipped with an undervoltage time–delay dropout motor reacceleration circuit. Dropout time shall be adjustable from 0–5 seconds. It shall be possible to remove or insert the reacceleration circuit by means of jumpers on terminal blocks. The time delay relay shall be an Agastat Series 7000, or as specified on the Data Sheets.

• Circuit Breaker Units - Mains and Feeders
• All circuit breakers shall be molded case, 3 pole, 600 volt. Minimum frame size is 100 ampere.
• Unless specified otherwise, circuit breakers and unit assemblies shall be UL listed for 42,000 RMS symmetrical ampere (AIC). The requirement for higher rating shall be as indicated on the Data Sheet.
• The type of circuit breaker required shall be as specified on the Data Sheet.
• High Resistance Grounding
• General
• When a high resistance grounding system is specified, the complete grounding system identified shall be provided, including the resistor with all components mounted/located in the motor control center.
• Unless specified otherwise, the continuous ground fault current shall be limited to 5 amperes maximum and 3 .5 ampere minimum.
• The resistor shall be connected directly to the MCC source transformer neutral with no disconnecting device in the circuit.
• The neutral ground resistor shall comply with EP 13–10–1 and the associated (filled out) Data Sheet, EP 13–10–1 DS.
• Current detection/measurement shall be by actual measurement of the current in the source neutral conductor (i.e., via a current transformer around the neutral conductor).
• Standard alarm only system

This system shall limit the ground fault current and alarm only. The system shall include:

• A ground fault alarm contact for Owner’s use (rated 125 VDC, 10 ampere).
• A test circuit with a normal–test light requiring manual reset to clear alarm and/or indication.
• Utility grade relays to monitor and initiate the ground fault alarm system.
• A switch to turn off the neutral ground detection scheme that removes all components from service except the neutral ground resistor and ammeter.
• An ammeter that indicates neutral current.
• Fault sensing via a current scheme utilizing a current transformer in conjunction with the monitor (protective) relay.
• “Pulsating” ground fault locating system

When specified the neutral grounding system shall be of the “pulsating” type to allow locating of the grounded circuit. The system shall include:

• A ground fault alarm contact for Owner’s use (rated 125 VDC, 10 ampere).
• Pulse test circuit actuated by a test “on–off” selector switch.
• Panel lights to indicate normal operation and fault condition.
• Fault condition light shall be supervised by a manual reset push button to clear the alarm/ indication.
• An ammeter that indicates neutral current.
• A pulse current that shall be less than 7.5 ampere.

• A switch to turn off the neutral ground detection scheme that removes all components from service except the neutral ground resistor and ammeter.
• A current probe (when specified) to measure pulsation currents in the load power conductors.
• Nameplates
• External visible permanent nameplates shall be provided identifying each instrument, instrument switch, meter, relay, control switch, push button, indicating light and load identifying number and name. The identification shall be the same as on the Data Sheet or drawings and approved by the Owner. Nameplates shall be laminated tags, white with black letters or black with white letters, as indicated on the data sheet (3/8 inch high minimum letter size) secured with screws or reusable plastic rivets.
• Equipment terminal blocks and devices shall be suitably identified and shall have the same identification as on the drawings.
• A permanent metal or plastic nameplate shall be provided that shall include, but not limited to, the following information:
• Manufacturer’s name, order number, date of manufacture.
• Bus ampacity, voltage (horizontal and vertical buses), bracing, bus material.
• Overall MCC unit rating in ampere RMS symmetrical as originally supplied.
• Provide nameplates for UL listing of vertical section(s) and for each unit.

TESTING AND INSPECTION

• Testing
• The Manufacturer shall perform all standard ANSI and NEMA production tests for all motor control centers. The testing shall include the Manufacturer’s standard tests, test requirements of this Practice and associated purchase documents, and conformance to NEMA ICS1–109 and UL Standard 845.
• Testing shall be done on completely assembled equipment. Interconnection wiring shall be via actual wiring harness supplied with the job and not temporary jumpers.
• Functional tests shall be done with the main bus energized at rated voltage and frequency.
• Testing shall include the requirements of paragraph 6.1 as well as the following:
• Mechanical operating tests shall be performed to insure proper functioning of operating mechanisms and interchangeability.
• The operation of shutters, mechanical interlocks, circuit breaker door interlocks, operating handles, trip mechanisms, electromechanical interlocks, physical clearances for mechanical and electrical isolation.
• The interchangeability of removable units designed to be interchangeable shall be verified as well as the rejection functions of non–interchangeable units.
• Functional operations test: All equipment shall be subject to an operational test. The test shall verify correctness of the circuit wiring and the functional operation of the control and power circuits and related components, and devices under simulated operating conditions.
• Device Testing: All devices shall be operated, set and checked for their functional characteristics in accordance with the instructions for each device and shall include such items as: pickup, drop out, time delay, contact operation.

• The phasing of all power buses shall be verified by application of power and measurement of phase sequence.
• High potential (hi–Pot) insulation tests.
• A dielectric test (hi–Pot) shall be performed on control wiring to confirm the insulation resistance to withstand breakdown. Test voltage and duration shall be as specified in NEMA ICS1–109.21.
• Power cables and buses shall be Hi–Pot tested, phase to phase and phase to ground for insulation breakdown resistance and circuit isolation, as specified in NEMA ICS1– 109.21
• Insulation resistance tests: All power cables and buses shall have insulation resistance tested with a 1000 VDC Megaohmeter. The minimum reading shall be 25 megohms.
• Witness Testing

When witness test is specified, the Owner shall witness the complete testing of all items outlined in paragraph 6.1 and the Owner approved contract documents.

DRAWING AND DATA REQUIREMENTS

All drawings provided for this equipment shall show equipment as specified and ordered. Typical drawings are not acceptable unless they are revised to show only the equipment being furnished. Drawings shall be supplied in the quantities shown on the Data Sheets.

• Information to be Supplied with Quotations
• Specific listing of any exceptions to those requirements specified.
• Equipment or features included but not necessarily specified. Include descriptive literature on proposed equipment.
• Sketches showing
• Equipment layout/orientation with dimensions.
• Proposed one line.
• The proposal shall include a complete list of unit prices consisting of the cost to add or delete any combination motor starter, or feeder circuit breaker of each size and type specified in the base bid.
• The proposal shall include a listing of all equipment/units AIC ratings and identification of equipment/units that are UL listed (Labeled) and those not UL listed (Labeled).
• Complete lists and descriptive data of all equipment and accessories proposed shall be included and any components not manufactured by the seller submitting the proposal shall be so noted as well as the Manufacturer and type proposed.
• Priced lists of normally recommended spare parts for the specified equipment shall be included in the quotation.
• Itemized list of unassembled equipment (including shipping splits).
• Example of the wire mark identification system to be used, see paragraph 5.3.1.10.
• Cost for witness testing, if specified.
• Information to be Submitted to The Owner for Approval after Receipt of Order

• Complete Structural drawings showing:
• Arrangement.
• Dimensional plan and elevation, front view, and other elevation views if pertinent.
• Conduit entrance locations and dimensions for both top and bottom entrance.
• Bus bar locations and configurations.
• Incoming and outgoing power cable terminator positions.
• Customer wiring terminal block locations, and all other terminal block locations.
• Anchor bolt locations.
• Grounding connections.
• Weight of equipment.
• One Line Diagrams: One line diagrams shall show all:
• Instrument transformers.
• Relays, and protective devices.
• Meters and meter switches.
• Other pertinent devices.
• Elementary Diagrams
• Elementary (schematic diagrams) shall be furnished for each different starter control scheme.
• Each elementary diagram shall show all control devices and device contacts, each of which shall be labeled.
• Detailed Connection (Wiring) Diagrams showing:
• All wiring within each unit.
• All interconnecting wiring between units.
• Identification of all terminals and terminal blocks.
• Clear identification, by some distinguishing method, of all wiring which is to be installed by Purchaser. This shall include spare auxiliary contacts and relay contacts which shall be wired to terminal blocks for future use.
• Tabular wiring diagrams are not acceptable.
• Detailed listing of all nameplates
• Certified Information to be Supplied
• All information requested in Section 6.1, 6.2 and 7.2.
• Installation and Operating Instructions: Installation and operating instructions shall cover all the equipment furnished including all protective devices, auxiliary relays and coordination curves of each protective device.
• Material List: A material list shall be furnished listing the quantity, rating, type, and Manufacturer’s catalog number of all equipment in each unit.
• Test Reports for testing outlined in paragraph 6.1 and additional requirements as detailed on the Data Sheets and/or contract documents.
• Listing of all equipment/units that are or are not UL listed.
• Spare Parts Listing
• When specified, certified information shall be provided in electronic format as detailed in Table 2.

SPARE PARTS

A complete spare parts recommendation based on the total purchase order is required within 60 days after the Manufacturer receives the purchase order. Spare parts recommendations shall include:

• A complete spare parts list, including parts location diagrams or drawings.
• List of priced spare parts as recommended by the Manufacturer to be on hand during plant start–up and the first year’s operation.

SHIPPING

• “Preparation for Shipment” shall be in accordance with Manufacturer’s standards, unless otherwise noted on the “Request for Quotation” and/or “Purchase Order”. The Manufacturer shall be solely responsible for the adequacy of the “Preparation for Shipment” provisions employed in respect of materials and application, to provide materials to their destination in ex– works condition when handled by commercial carrier systems.
• Any components that are shipped separately from their respective motor control centers shall be properly tagged with both their compartment (motor) number, and the number of the motor control center of which they are a part.
• Control relays, magnetic contactors, and any other components with moving parts which might be damaged in shipment, shall have all such moving parts securely blocked and braced.
• Each “shipping section” shall be provided with a permanently–attached, readily–visible, identification tag.

10.0 TABLES

TABLE 1

MINIMUM WIRE SIZES FOR POWER CIRCUITS

TABLE 2

CERTIFIED INFORMATION REQUIRED IN ELECTRONIC FORMAT (1 )

NOTE:

(1) Information is for all equipment supplied with the motor control center.

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