Section 13 — Electrical

Adjustable Frequency Drives for Large Frame Induction (Medium Voltage) Motors 300 HP & Larger

IPE Engineering Practice IPE-EP-13-26-2

Document number: IPE-EP-13-26-2 · Section: 13 — Electrical

SCOPE

• This specification covers the materials, design and fabrication of adjustable frequency drives (AFD’s) sizes 300 HP and larger, for speed control of medium voltage large frame squirrel cage induction motors for petroleum and chemical industry service.
• This practice is appropriate for attachment to an inquiry or purchase document when accompanied by the referenced IPE Engineering Practices and completed Data Sheet from EP 13-26-2 DS.
• 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.

REFERENCES

• The latest published edition of the following Standards and Codes shall be used with this Practice:

STANDARDS AND PUBLICATIONS

STANDARDS AND PUBLICATIONS (CONT.)

3.0

3.1

3.2

3.3

3.4

3.5

3.6

4.0

5.0

5.1

5.1.1

5.1.2

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

The AFD will be located in an environmentally controlled building classified as a “General Purpose Area” within a petrochemical processing facility. The ambient temperature range of the building will be controlled to levels suitable for the reliable operation of the AFD as specified by the AFD Manufacturer. The altitude will be 3300 feet or lower. In most cases the AFD will be located in a substation housing medium and low voltage distribution equipment.

DESIGN, CONSTRUCTION AND MATERIALS

General

The design of the AFD and the provided diagnostics shall allow maintenance personnel not familiar with this type of equipment to perform inspections and repairs by exchange of components in a timely fashion without the use of special tools and skills.

All components and subassemblies used shall be suitable for the severe environmental and operating conditions typically found in petrochemical facilities. As a minimum, the following is required:

• Moisture and fungus proof printed circuit boards and electrical components.
• Hermetically sealed potentiometers, trim capacitors and relays.

• Corrosion resistant exposed contacts. Traces of H2S will be in the cooling air.
• Input/output compatibility of all external signals with standard computer interfaces.
• Immunity to externally generated electrical noise and harmonics.
• Immunity to externally generated RF signals.
• When the input, output, and/or bypass switches are part of the AFD supplier’s scope, they shall conform to the appropriate Practices; EP 13–5–2, EP 13–6–1, EP 13–6–2 and EP 13–25–1. If the AFD Manufacturer’s scope included the motor it shall conform to EP 13–3–2. In all cases the above shall be selected from the current Owner’s approved vendors list.
• The equipment described herein (total AFD package) is considered a complete and functional drive package, operating in a fully automatic mode, largely independent of operator interface, and with prime emphasis on utmost reliability. Routine maintenance operations shall not require a shutdown of the drive system between the scheduled plant required maintenance activities every five years.
• The AFD Manufacturer shall perform any modifications to a standard product to meet this specification only. Distributor or system integrator changes to the AFD Manufacturer’s product are specifically disallowed.
• The AFD shall include the incoming device specified on the Data Sheet (see Paragraph 5.1.3 above) power factor correction/harmonic filter unit if required, input rectifier, 3 winding or multi– pulse drive isolation transformer, 18 pulse or greater converter section, output inverter and control logic section with specified annunciation. All components specified including input device, power factor correction/harmonic filter (if required) and transformer shall be integral to the AFD line up, factory wired and tested as a complete system.
• The use of output step–up transformers shall only be used when approved by the Owner. If output transformers are used, they must be technically justified to include assurances that a constant torque load (if specified) or high starting torque limitations have been analyzed to insure that the output transformer will not saturate.
• Performance and Ratings
• AFD’s shall meet all the requirements of the latest edition of IEEE 519 for total harmonic voltage and current distortion and the requirements of this specification. Where conflicts arise between this specification and IEEE 519–1992, the more restrictive shall be the default requirement.
• THD Limits – The point of common coupling for all harmonic calculations and field measurements for both voltage and current distortion shall be defined as the primary connection of the AFD. The short circuit current at the point of common coupling shall be as specified on the Data Sheet.
• The maximum allowable total harmonic voltage distortion at the input of the AFD of shall not exceed 3% regardless of operating point.
• The maximum total harmonic current distortion at the input of the AFD shall not exceed 5% regardless of operating point.
• If harmonic filters are required to achieve THD requirements, they shall be provided by the AFD Manufacturer as a part of the AFD system. The AFD Manufacturer shall be responsible for the design and performance of the filter.

• Unless specified otherwise, each AFD supplied shall have its compliance to the specified THD limits verified at the point of common coupling with the AFD connected to the users power system. Compliance shall be verified with on–site field measurements with and without the AFD operating. The THD limits shall be verified with the AFD operating at a speed range/loading range mutually agreed to by the Owner and the AFD Manufacturer at the time of award. All costs for testing shall be borne by the AFD Manufacturer and quoted as a separate line item.
• Unless specified otherwise, each AFD supplied shall have its compliance to the specified THD limits verified at the point of common coupling with the AFD connected to the users power system. The THD limits shall be verified with the AFD operating at a speed range/loading range mutually agreed to by the Owner and the AFD Manufacturer at the time of award. All costs for testing shall be borne by the AFD Manufacturer and quoted as a separate line item.
• The AFD output shall produce no damaging and/or operational limiting pulsation torque at the motor output shaft to the driven equipment. The AFD Manufacturer shall assume responsibility for damage to the Owner’s equipment caused by pulsation torque. If torsional analysis is required, it shall be provided by the AFD Manufacturer as part of the scope of supply and quoted as a separate line item.
• AFD Ride Through for Electric System Disturbances
• The AFD system (output and controls) shall be capable of riding through a minimum of a 5 cycle loss of total AFD system power.
• The AFD shall be capable of continuos operation during an input voltage, drive and/or control voltage, reduction down to 70% of nominal. During the voltage reduction within the specified limits, the AFD shall automatically ramp down to a reduced speed operation. When power is restored, the AFD shall be capable of automatically ramping back up to the operating speed as indicated by the input control setpoint.
• The AFD system shall maintain a 0.95 minimum true power factor from 30 to 100 percent speed. The AFD system including power factor correction and/or harmonic filter shall never have a leading power factor. If a power factor correction unit is required, it shall include a separate input isolating contactor with fuses, power factor correction capacitors (5KV class) and series harmonic decoupling reactors, all mounted and wired in a NEMA 1 Enclosure.
• Only when specified, the AFD shall be designed to provide an inverter/converter with an N–1 failure capability to enhance reliability. An N–1 system, if available may be quoted as a separate item.
• The AFD output shall be suitable of operating the Owner’s specified (new or existing) squirrel cage induction motor without any derating or reduction in motor life.
• The AFD shall not induce any appreciable audible noise increase in the driven equipment over the entire drive speed range. The noise level of the motor shall not increase more than 5 dBa over that of normal line operation. If the noise level of the motor will increase more than 5 dBa above normal, it shall be the Owner’s responsibility to approve the higher noise level.
• The AFD shall be able to operate at 100% rated current continuously and at 115% of rated current for one minute.

• The AFD shall provide direct control of the motor without requiring motor mounted tachometers or shaft position encoders on variable torque loads.
• The AFD power capacitor voltage shall be automatically discharged below 50 volts within one minute or less after de–energization of the AFD per NEMA and NFPA/NEC.
• When specified, the AFD shall be capable/configurable for closed loop vector control.
• Transformers, Reactors and Filters
• All outdoor power transformers shall be oil filled and be supplied by one of the following manufacturers: ABB Co., General Electric Co., Cooper Power Systems. The use of outdoor dry type transformers, reactors and filter inductors shall require the approval of the Owner.
• Dry type transformers, reactors, etc. supplied with AFD’s shall:
• Have a suitable K factor for the service but be no less than K-12 for variable torque loads, K-20 for constant torque loads, K-20 on SCR 6 Pulse converter drives.
• Have a 115ºC or lower temperature rise.
• Provide annunciation for high temperature and high-high temperature (trip temperature).
• Be supplied with input surge/lightning arrestors.
• Oil filled transformers shall comply with the AFD Manufacturer’s performance criteria for drive application but shall also be in compliance with EP 13–4–1 and a completed, Owner approved Data Sheet per EP 13–4–1 DS.
• AFD’s requiring transformers, reactors, and filters shall have these devices supplied as part of the AFD package.
• Controls
• The control logic section shall be fully digital.
• All drive adjustments, programming, annunciation and drive diagnostic output shall be stored in a non–volatile memory (EPROM) to insure no information loss for loss of AFD input power.
• Local control and programming shall be via a door-mounted membrane keypad with an integral LCD display. Local manual and remote drive controls shall be as specified on the Data Sheet and/or as specified elsewhere in this Practice.
• Password security shall be provided to prevent undesired resetting of the microprocessor based digital controller.
• Unless specified otherwise on the data sheet, RS-232 port shall be provided for Owner’s use for computer or printer interface. AFD parameters, fault log and diagnostic log shall be downloadable for hard copy printout via the specified port and owner’s printer.
• All displayed alarms, faults and diagnostics shall be displayed in English, fault codes are unacceptable.
• All controls/pilot devices mounted on the AFD, 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 ICS 2-216 as a minimum, and be U. L. listed.
• All indicating lights shall be LED “cluster” push to test type.

• Control switches, meters, indicating lights, control devices, etc. shall be mounted on the front door panels and arranged in logical, symmetrical manner that shall be approved by the Owner prior to fabrication.
• Unless specified otherwise on the Data Sheet, local controls mounted on the AFD shall include but not be limited to the following:
• Manual speed control potentiometer
• Local-off-remote switch
• Guarded stop push–button
• Guarded on push–button
• Unless specified otherwise on the Data Sheet, the following user inputs for speed control shall be provided as a minimum:
• 0-10 volt
• 4-20 m AMP
• The AFD shall have a communication interface that shall be compatible to the Owner’s equipment specified on the Data Sheet.
• Power Bus and Grounding
• Main power bus
• The main power bus shall be copper with tin plated joints. All bus splice and connection points shall be via two or more bolts.
• All power buses shall be completely isolated and insulated/fully clad with flame retardant non-hygroscopic, high dielectric insulation. Joints and terminations shall be insulated using boots and/or taping.
• All power bus shall be suitably braced for the fault current specified. As a minimum, the main power bus shall be braced and tested in accordance with NEMA/EEMAC ICS 2-324 through ICS 2-2.325, and UL 347.
• Ground bus
• A 1/4 inch by 1 inch copper ground bus shall be provided along the entire length of the drive control line–up.
• The ground bus shall be easily accessible from the front of each drive compartment for ease of connection to the Owner’s ground.
• Wiring
• Provide adequate space for customers power wiring and cable terminations. Unless approved otherwise by the Owner, all control and power wiring shall be accessible/ installed via front access.
• Customers power and control wire entry shall be as noted on the attached Data Sheet.
• All internal AFD wiring between splits shall be wired either to terminal blocks for interconnection wiring or to listed wiring plugs/jacks. All wiring for external wiring to the AFD shall be via barrier terminal strips suitable for termination of the Owner’s insulated barrel compression type spade lugs. Terminal blocks for different voltages or systems shall be isolated from one another.
• All Purchaser or field wiring connections must be clearly defined on all ladder and wiring diagrams as well as the connection points in the equipment.

• Wire labeling shall be plastic, slip on (Barrel), with typed–on identification. Other types of wire marks shall require the approval of the Owner.
• Mechanical
• The entire AFD shall be housed in metal enclosed free standing dead front vertical assemblies rated NEMA 1 as a minimum.
• The low voltage/control module shall be accessible without shutting the controller down when opening the compartment door.
• All access for customer wiring, AFD maintenance and operation shall be via the front of the AFD.
• All cubicles/compartments that require routine inspection, maintenance, or repair shall be furnished with hinged doors. All other covers shall be bolted panels.
• When air cooling is used, the AFD Manufacturer shall submit with their proposal the expected heat rejection from the AFD equipment at worst case operating conditions. This will insure proper sizing of air conditioning equipment to allow continuous operation under worst case conditions.
• System/Load Protection
• The AFD Manufacturer shall provide their standard protection package that shall include but not be limited to the following:
• AFD input protection
• Undervoltage trip
• Overvoltage trip
• Instantaneous fault overcurrent trip
• Ground fault trip
• Loss of phase trip
• Overload shutdown
• Lightning/surge protection
• AFD system
• Control logic power failure trip (after ride–through is exceeded)
• Air cooling system failure shutdown
• Overtemperature shutdown
• Load side protection
• Short circuit trip
• Overload shutdown
• Overvoltage trip
• Motor overspeed trip
• Loss of phase trip
• Motor RTD shutdown
• Provide provisions for user’s external relay/system trip signal.
• All voltage and current trip/shutdown functions shall be both magnitude and time adjustable.
• All converter devices shall have fuses upstream to protect the transformer secondary windings.
• Annunciation

• All items designated as alarms/annunciation shall be individually identified and available for review and analysis either via individual indication or readout from the control panel.
• In addition to all other alarm functions a common trouble alarm contact (Form C) shall be provided for the customers use, rated 120V, 5 amp.
• All items in section 5.8 of the specification shall be annunciated.
• The AFD Manufacturer shall provide their standard annunciation points. In addition the following items shall be annunciated.
• Low cooling air flow in the AFD
• AFD transfer to backup fan cooling system
• Provide the ability to scan annunciation output for faults/events during the condition of a complete loss of input and control power. If this is not a standard function quote this as an option as a separate line item add/delete.
• Nameplates
• All individual subassemblies and components inside the cubicles/compartments shall be permanently identified by plastic tags or labels that use the same identification as the wiring and schematic diagrams.
• All devices mounted on doors and accessible from the outside shall be identified with permanently engraved laminated plastic tags with black letters on a white background that are fastened with plastic rivets or stainless steel screws.
• Metering / System Protection
• Unless specified, the AFD shall be supplied with GE PQM meters for both AFD input and output to measure harmonics, power factor, amps, volts and watts.
• Protective input and/or output relays shall be provided as specified on the Data Sheet. These devices are not intended to replace the AFD supplied devices, but are meant to supplement the AFD standard supplied devices.

6.0 TESTING

• The AFD package shall be fully tested to the extent possible as a complete unit prior to shipment to the owner’s facility.
• The Owner shall witness the complete testing of all items outlined in this section and the Owner approved contract documents.
• Testing shall be done on completely assembled equipment, interconnection wiring shall be via actual wiring harness supplied with the job and not temporary jumpers.
• The Manufacturer shall perform all their standard factory tests. Testing shall also include but not be limited to the following:
• Insulation resistance tests of all power and control circuits.
• Operational tests of all control, instruments and relay circuits.
• Operational tests of all power circuit breaker mechanisms, switches and interlock devices.
• Functional tests of all subsystems, such as thyristor converters, control systems, microprocessor controls, etc. with actual or simulated field signals.

• Verification of contract guaranteed efficiencies of the equipment within the AFD Manufacturer’s scope of supply.
• Any equipment supplied as part of the AFD Manufacturer’s scope, e.g. transformers, motors, etc. shall be tested in accordance to the applicable IPE Engineering Practice and its associated Data Sheet.
• Verification of operation during loss of AFD voltage and reduction of AFD voltage per paragraph 5.2.4.
• When specified on the Data Sheet, an AFD burn–in shall be accomplished by energizing and operating the AFD for a minimum of 50 hours in the factory to insure all components and subsystems are operating properly. Should a component, system, or subsystem failure occur the AFD system shall be run for another 50 hours after replacement of the failed part.
• The AFD Manufacturer shall use GE–multilin PQM meters or Owner approved equal on the input and output of the drive to measure harmonics, power factor, amps, volts and kilowatts to verify harmonics and efficiency.
• When a factory load test is specified, the job driver shall be used with the motor run on a dynamic load such as a dynamometer to test the AFD and motor combination across the specified speed/load range. The load test will be repeated, field installed, by the AFD Manufacturer, using identical test instruments. Data will be reviewed and analyzed by the AFD Manufacturer with results sent to the Owner.

DRAWING AND DATA REQUIREMENTS

All drawings provided for the equipment shall show the equipment as specified and ordered. Typical drawings are not acceptable unless they are revised to show only the equipment being furnished.

• Information to be Supplied with Quotation
• Specific listing of and exceptions to those requirements specified.
• Equipment features included but not necessarily specified.
• Recommended spare parts list with prices that are required for start–up and for extended operation of five years between maintenance shutdowns.
• Quote must be for equipment specified. However, Manufacturer recommended alternatives are encouraged and may be quoted as alternatives with specific rational and associated price add/deduct.
• Sketches/drawings showing:
• Arrangement
• Dimensional plan and elevation, front views, and other elevation views if pertinent.
• Cable/wire/conduit entrance locations with dimensions of access areas.
• Guaranteed efficiencies for the operating range to include but not limited to 50, 75, 100% of speed/load range of the AFD.
• Guaranteed THD levels at the input and output of the AFD.
• Calculated performance curves of AFD system (over speed range specified) for the following:
• Efficiency of the entire drive system versus speed/load.

• Drive torque (normal and limit) versus speed.
• Input power factor versus speed/load.
• Predicted noise emission data for the AFD and motor.
• Worst case heat rejection rates for the AFD and worst case heat rejection rates over the specified operating range.
• Detailed description of all factory and field testing included with the quotation.
• Detailed description of the equipment, e.g. converter, controls, microprocessor, rectifier etc.
• Cooling air requirements for all major items. Provide details for Owner’s cooling requirements to insure reliable operation over the entire range of specified operation.
• Shipping weights, unit splits, and detailed description of field assembly required.
• Description of how circuit boards, electronic elements are inspected and tested.
• Detailed description of alarms/annunciation, protection, metering and diagnostics, etc.
• Bidders shall include with their proposal a complete reference list of identical and/or similar AFD installations, including the following:
• Year of installation
• Rating and speed of drive
• Customer’s name and location
• Type of driven equipment
• The AFD Manufacturer shall provide a preliminary Harmonic study analysis of the Owner’s facility to determine the effect of the AFD on the existing electrical system and the driven load equipment. If filtering is required the bidder shall include a quote for equipment necessary to reduce the harmonics to acceptable levels per the requirements of this specification and the experience of the AFD Manufacturer.
• Guaranteed delivery date after receipt of order.
• Provide a detailed description of all Manufacturer’s recommended factory tests and the Owner’s specified tests to be provided as part of the witness testing.
• Information to be Submitted for Approval After Receipt of Order
• Manufacturing, testing and shipping schedule.
• Tabulation of required certified/guaranteed performance information to be provided.
• Complete mechanical/structural drawings showing:
• Arrangement
• Dimensional plan and elevation, front view, and other elevation views if pertinent
• Conduit (wire and cable) entrance locations
• Bus bar and ground bus locations and configurations
• Incoming and outgoing power cable compartment locations, dimensions and bracing provided
• Purchaser’s interconnection terminal block locations and location of all unit interconnection blocks/plugs
• Identification of all items requiring field assembly

• Recommended installation instructions to include foundations, lifting, etc.
• Weight of equipment furnished
• Power system one line diagram (as a minimum shall show)
• Instrument transformers
• Protective relays
• Metering
• All devices shall be identified using ANSI C37.2 designations
• Elementary/Schematic and Ladder Diagrams
• Each elementary diagram shall show all protection, control devices and all device contacts.
• The AFD Manufacturer shall provide all block and ladder diagrams for all closed loop controls.
• The AFD Manufacturer shall provide block diagrams of flow sheets and open loop.
• The AFD Manufacturer shall provide a final complete harmonic study and evaluation for the as designed system/equipment. If the harmonics exceed specified levels, the AFD Manufacturer shall provide complete specifications for the recommended filtering equipment.
• Detailed information on the as supplied AFD cooling requirements and heat rejection rates.
• Detailed information on all standard metering and protective devices supplied and those offered as options.
• Certified Information to be Supplied
• All the information requested in Sections 6.0 and 7.2 of this Practice.
• Installation, operating and maintenance instructions covering all the equipment furnished.
• A material list indicating the quantity, rating, type, and Manufacturer’s catalog number of all the equipment furnished.
• Recommended spare parts list.
• Complete test reports for factory and field testing.
• Quantities for drawings, test reports and manuals shall be as specified on the Data Sheet.

8.0 SPARE PARTS

A complete recommended spare parts list with cost and delivery after receipt of order shall be provided with the AFD suppliers bid. The spare parts requirements and cost shall be an integral part of the evaluation process. Spare parts shall be of sufficient quantities and type to satisfy the requirements of paragraphs 5.1.1, 5.1.4 and 7.1.3 of this Practice.

9.0 SHIPPING

• Preparation for shipment shall be in accordance with the AFD Manufacturer’s standards, unless specified otherwise by the Owner. 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 cubical/compartment shall be properly tagged with both their compartment number, and identification that coincides with the installation drawings.
• Each shipping section shall be provided with a permanently–attached, readily–visible, identification tag.

10.0 TABLES

TABLE 1

CERTIFIED INFORMATION REQUIRED IN ELECTRONIC FORMAT

FOR ADJUSTABLE FREQUENCY DRIVES FOR LARGE FRAME INDUCTION MOTORS, 300 HP AND LARGER PER EP 13–26–2

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