Rotary Frequency Converter Specification
The following specification is intended for use by consultant engineering firms to provide bidding specifications for products with the quality and performance characteristics required for a rotary frequency converter system. This specification describes a three phase rotary frequency converter system and all its necessary operations. In order for a response to this request to be considered it shall require submittal of a proposal of adequate depth to fully define and identify the rotary frequency converter being offered. The rotary frequency converter, hereafter, shall be referred to as the “RFC”.
1.2 Furnished with Equipment
- Factory Test Report
- Protective Packaging
- Installation Drawings
- O&M Manual
- Warranty Statement
1.3 Documents & Standards
National Electrical Code, NFPA 70-2005.
American National Standards Institute (ANSI).
NEMA Publications Number PB-1 and MG-1.
IEEE Standards 45.
Occupational Safety & Health Act (OSHA).
Local Codes & Authorities having jurisdiction for this installation.
1.4 System Description
1.4.1 The RFC shall be a rotary type with regenerated true sinusoidal waveform, with a regulated phase/voltage relationship output. The RFC and associated controls shall provide a means of electro-mechanically converting the Alternating Current (AC) power source to the desired output frequency. Electro-mechanical conversion inherently provides power conditioning, as well as, true electrical isolation through the mechanical couple.
1.4.2 [Induction – Synchronous] or [Synchronous – Synchronous] Motor-Generator (M-G): This portion of the RFC system that shall generate new, clean AC true sinusoidal, phase/voltage relationship, regulated power to be supplied to the critical loads. The winding of the motor and generator shall be at least 23 cm (9″) apart allowing for total electrical isolation from the input to output.
1.4.3 The RFC shall be a single system rated to supply the full load as specified herein. A (N+X) paralleled RFC system shall be utilized for accomplishing redundancy, or for building power as required for the application. A redundant RFC system shall have each module rated to supply full load as specified. A paralleled RFC intended for building power shall be rated as specified by the requirement.
1.5 System Operation
1.5.1 Normal: Alternating current (AC) line power shall be supplied continuously to the RFC. The generator output shall be connected to the critical load within the specified voltage and frequency range.
1.5.2 Input Power Disturbance: The RFC may drop off line when a disturbance to the normal AC power supply is encountered. Once the input power has been restored the RFC will automatically restart and resume operation. The automatic restart is a functional option when specified accordingly.
1.5.3 Output Power Disturbance: If a disturbance to the downstream equipment being powered by the RFC is encountered, the RFC system will continue to supply conditioned AC power to the load. If the downstream disturbance could possibly short circuit the output of the RFC then the RFC will automatically shut down in order to protect its critical components. The RFC will not continue operation until manual restart is engaged.
1.6 Quality Assurance
1.6.1 The manufacturer shall have a Quality Assurance (QA) program in place with inspection of incoming parts, modular assemblies, and final products. The manufacturer shall have a designated QA manager who is responsible for overseeing the overall QA process, as well as, Quality Control (QC) representatives responsible for actively overseeing the manufacturing process.
1.6.2 A final test procedure for the product shall include a check of all performance specifications and a minimum “burn in” period. An on-site test procedure shall include a check of controls and indicators after installation of the equipment.
1.6.3 Storage, Handling, & Delivery: The equipment shall be shipped on a wooden pallet suitable for forklift handling. The equipment shall be covered with clear plastic sheeting to prevent dust and dirt from entering the unit during shipment. For international shipment, a wooden pallet will be constructed of treated wood and shall meet all other specifications required for international freight.
1.7.1 Proposal: Catalog cut sheets and/or data sheets describing the proposed equipment shall be submitted with the proposal. A users listing shall be available upon request giving company names, locations, and systems installed. All deviations from this specification shall be listed and included with the proposal.
1.7.2 Receipt of Order: A minimum of two sets of installation drawings showing outline dimensions, weights, connections, and a one-line diagram of the RFC shall be sent to the purchaser to be used in planning the installation of the system.
1.7.3 Formal Approval: If a formal submitted approval is required for the project then the following should be requested, submitted, and approved before design/construction of the RFC commences:
- Equipment Installation Outline
- External Cabling Connection Diagram
- Equipment One-Line Power Diagram
- Equipment Elevation Drawing
- “Other” Site Evaluation Diagrams
1.7.4 Delivery of Equipment: As a minimum, the following shall be provided with the equipment upon its arrival to the final destination:
- Operation & Maintenance Manual
- System Installation Procedures
- System Operation Procedures
- System Troubleshooting Instructions
- System Maintenance Milestones
- Recommended Spare Parts List
- Final Test Report Copy
1.8.1 The manufacturer shall state the warranty of the equipment, and in no case shall it be less than 12 months after start-up or 18 months after shipment, whichever occurs first. A warranty statement will be provided with the equipment and included as part of the overall O&M manual.
2.1 System Size
2.1.1 The RFC system will be sized to handle any application up to 2,000kVA (LV) and 15,000kVA (MV).
2.2 RFC Input
2.2.1 Input Voltage/Frequency: 208, 440, 460, 480, or 600 Volts (LV) and 4160, 7200, or 13800 Volts (MV) at 60Hz and 208, 380, 400, 415, or 600 Volts (LV) and 3300, 6600, 11000 Volts (MV) at 50Hz. These three phase input voltages are available in 3-wire (DELTA) or 4-wire (WYE) configurations.
2.2.2 Voltage Range: +15% to -20% of Nominal.
2.2.3 Voltage Transient Impulse: Up to 1500V for no more than 1 millisecond.
2.2.4 Starting Inrush: Starting the RFC “Across the line” will be (6x) the nominal input amperage. Starting the RFC using a “Reduced voltage starter” (WYE-DELTA or Series Parallel) will be (3x) the nominal input amperage.
2.2.5 Power Factor: 0.8 Leading to 0.8 lagging.
2.3 RFC Output
2.3.1 Output Voltage/Frequency: 208, 440, 460, 480, or 600 Volts (LV) and 4160, 7200, or 13800 Volts (MV) at 60Hz and 208, 380, 400, 415, or 600 Volts (LV) and 3300, 6600, 11000 Volts (MV) at 50Hz, and 200/115 and 208/120 Volts (LV) at 400Hz. These three phase output voltages are available in 3-wire (DELTA) and 4-wire (WYE) configurations.
2.3.2 Voltage Regulation: 1% Steady-state.
2.3.3 Recovery Time: 0.5 Seconds.
2.3.4 Voltage Adjustment: +/- 10% of Nominal.
2.3.5 Frequency: [25Hz, 50Hz, 60Hz, 100Hz, 200Hz, and 400Hz]
2.3.6 Transient Voltage Regulation: +/- 8% with 50 step load.
2.3.7 Power Factor: 0.8 Lagging.
2.3.8 Harmonics: 5% RMS (Total) and 3% RMS (Single).
2.3.9 Phase Separation: 120° +/-1° (Balanced Load). 120° +/- 3° (Unbalanced Load).
2.3.10 Overload Capacity: 110% (Continuous), 125% (10 Minutes), 150% (1 Minute).
2.4.1 The equipment shall be suitable for installation indoors (altitude 0 to 12,000 meters or 0 to 4,000 feet) with ambient temperatures ranging from 0° to +40°C (32° to +104°F) with 1% de-rating for each 1°C above 40°C up to 50°C, and relative humidity from 0% – 95% non-condensing.
2.4.2 Site Conditions:
- Ambient: 0° to 40°C (32° to 104°F) with 50° and 55° (Optional).
- Humidity: 0% to 95% Non-condensing.
- Audible Noise: 90dB Open Frame. Lower noise levels (Optional).
- Construction: Suitable for indoor application. Outdoor enclosures (Optional).
- Bearings: Grease lubricated, Anti-friction type.
- Service Factor: Continuous duty, 24-hour service.
2.5 Physical Characteristics
2.5.1 Physical Description, the RFC system shall be built with the following elements:
- Brushless, two bearing [Induction] or [Synchronous] motor
- Brushless, two bearing synchronous generator
- Reduced current motor starter
- Motor controls
- Generator controls
- Motor input circuit breaker
- Brushless direct connected AC exciter with rotating filters
- Belts and sheaves (4 Bearing Models)
- Generator output circuit breaker
- Common mounting steel base
- [Spring] or [Rubber] Vibration isolators
2.5.2 Relay Logic Controls (Standard): The RFC system shall be built with the following elements:
- Motor Control: START switch of the RFC that activates the motor starter.
- Motor Starter: Reduced voltage start system.
- Instruments: Metering (2% Accuracy) shall monitor the following points: AC Input Voltmeter (Each line voltage with selector switch), AC Input Current (Each phase with selector switch), AC Output Voltage (Each line-to-line voltage with selector switch), AC Output Current (Each phase with selector switch).
- Voltage Adjustment Range: Control shall provide +/- 10% adjustment from nominal.
- Fault Detectors: The RFC shall be equipped with protective devices which shall shut the unit down and activate internal latched indicators. These indicators shall retain the fault indication after the rotational energy has stopped to simplify troubleshooting. The following faults will be detected: Output Over Voltage, Output Under Voltage, Starter Overload, Output Under Frequency, Motor Overload, Motor Over Temperature, and Generator Bearing Over Temperature.
- Status Lights: Indicator lights shall indicate (Motor On), (Load On), and (System Fault).
- EPO Button: This feature provides for the interface of the customer supplied “Emergency Power Off” via a set of switchable normally close/normally open dry contacts.
- Controls: The RFC control shall be mounted in a floor standing cabinet, or on the base with the motor generator set, depending on the rating and configuration chosen.
- Power Outage Protector: The RFC shall be equipped with protector circuits, and in the event of a sustained power outage, the output will be disconnected when the output frequency decays to a preset level. Furthermore, the motor shall be protected from return of utility power before the RFC has coasted to a complete stop.
2.6.1 Quality: All materials, parts, and components used will be new and of the highest grade. Brackets and securing hardware shall be electroplated with corrosion resistant material. Internal wiring conductors shall be combined into cables, or bundles and shall be tried securely together.
2.6.2 Design: The RFC system shall use components of adequate rating to provide an expected service life of over twenty (20) years continuous duty and ten (10) years without component replacement, provided that routine maintenance procedures are carried out.
2.6.3 Experience: The manufacturer should have at least ten (10) years experience designing, constructing, and servicing rotary frequency converter systems. Experience with solid state frequency converters or other rotational power quality systems will not be accepted as applicable experience.
2.6.4 Maintainability: No regular maintenance service operations are required except for a yearly Preventative Maintenance (PM) review. A (N+X) paralleled or other unique “project specific” modifications may require a more rigorous maintenance platform in order to guarantee longevity of operation and end of life (EOL). Maintenance may be done at more frequent intervals if desired.
2.6.5 System Layout: Modules and sub-assemblies shall be mounted in open construction design so that each may be easily replaced. The equipment shall be constructed so that each component can be replaced without the need for specialized tools.
2.6.6 Installation: At installations where unusual concentrations of moisture, vapors, dust, and other particles may impinge upon windings. Rotating systems require clean inlet air. Contaminants such as magnetic, metallic, conductive, abrasive, or chemically active materials must be avoided in the airflow by effective filtering. Materials such as dust or lint, which can accumulate and block ventilation passages, must also be filtered.
2.7 Optional Features
2.7.1 Two Beating, Common Shaft Design: This RFC design allows the frequency conversion to be based on the number of motor poles and generator poles. The two bearing, common shaft design differs from the four bearing configuration in that no belts or sheaves are utilized in the frequency conversion process. A common, single shaft allows for lower maintenance, increased reliability, and longer system end of life (EOL). The manufacturer recommends four bearing systems for requirements below 300kVA and a two bearing solution for requirements for above 300kVA.
2.7.2 PLC Based Color Touch Screen Controls:
- Motor Control: The START pushbutton on the RFC touch screen interface will activate the reduced current motor starter.
- Motor Starter: Reduced current motor starting shall be accomplished by one of the following methods: Series Parallel, WYE-DELTA, Pony Motor, and Current Limiting Reactor. Depends on system specification and rating; consult factory for details.
- Metering (1% Accuracy) shall monitor the following points: AC Input Voltage (Each Phase), AC Input Current (Each Phase), AC Output Voltage (Each Phase), AC Output Current (Each Phase), and System Output Power (kVA).
- Voltage Adjustment Range: Output voltage control shall provide up to a 10% adjustment range from nominal using the color touch screen HMI.
- Fault Detectors: The RFC shall be equipped with protective devices, which signal the PLC to shut the unit down and alarm. Each fault will be displayed on the touch screen for clarity. Each fault message shall have a date and time stamp to allow easy recognition of the latest fault. The fault messages shall be retained after the motor generator has stopped and after cycling power to simplify troubleshooting. The following faults will be displayed: Output Under Voltage, Output Over Voltage, Starter Overload, Output Under Frequency, Motor Overload, Motor Over Temperature, and Generator Bearing Over Temperature.
- Event History: The PLC shall store the last 50 events and faults. The memory space shall be FIFO after it is full. Each event shall have a date and time stamp.
- Emergency Power Off (EPO) Button: This feature provides for the interface of the customer supplied “Emergency Power Off” via a set of switchable normally closed/normally open dry contacts.
- Controls: The RFC controls shall be mounted in a floor standing cabinet, or on the base of the motor generator set, depending on the rating and configuration chosen.
- Power Outage Protector: The RFC shall be equipped with protector circuits and, in the event of a sustained power outage, the output will be disconnected when the output frequency decays to a preset level. Furthermore, the motor shall be protected from return of utility power before the RFC has coasted to a complete stop.
2.7.3 Remote Monitoring System: There are many methods that can be utilized to allow the user to interface with the RFC system giving them a wide range of monitoring and control options:
- Modbus: Modbus over serial line with RTU protocol. A modbus serial port is provided to remotely access the RFC modbus registers and status bits. All the RFC analog metering information, operational status information, and messaging will be provided via Modbus protocol. Modbus over TCP is also available. An Ethernet port is provided to remotely access the RFC Modbis registers and status bits the same as RTU but with a TCP interface that runs n Ethernet. Please contact factory for additional information.
- Web Based: The web based remote monitoring/control feature puts the user at the control screen of the RFC, anywhere in the world, via the world wide web (www). The web interface can be programmed to give limited access based on responsibility or full access of the whole user interface. Please contact the factory for additional information.
- Remote Color Touch Screen: All RFC analog metering and operational status are displayed on a remote screen that can be installed in secure or remote locations. All real-time data is displayed with a dedicated communications link. Link via Profibus DP or Profinet Industrial Ethernet. Please contact the factory for additional information.
2.7.4 Exhaust Silencer: The RFC will be equipped with a sound attenuation device to reduce exhaust noise emission to less than 80dB when measured at industry standards. The exhaust silencer will be an integral part of the overall RFC assembly.
2.7.5 Sound Attenuated Enclosure: The RFC will be built into a sound attenuation enclosure to reduce the noise emission to less than 75dB when measured at industry standards. The attenuated enclosure will enclose the RFC, and shall be equipped with noise absorbing material which won’t restrict air flow. It also allows an extra level of protection against dust and other particles.
2.7.6 Outdoor Rated Enclosure: The RFC will be built to endure the harshest outdoor environments – sand, snow, rain, salt, etc. This enclosures will be built to NEMA 3, 3R, 4, 4X, 12…standards. For large systems (300kVA+) or “turn-key” applications the RFC can be built into an ISO container allowing for easy transportation, installation, and maintenance.
3.1.1 The manufacturer shall design, build, and test the RFC system. If requested by the customer, the manufacturer shall arrange shipment of the RFC to their requested destination.
3.1.2 The manufacturer shall prepare and deliver the required drawings and manuals with the equipment.
3.2 Site Preparation
3.2.1 The owner shall prepare their site for installation of the equipment.
3.2.2 The owner shall arrange for local electricians to install the equipment.
3.2.3 The RFC shall be installed in accordance with local codes and the OEM’s recommendations.
3.3 Field Service Start-up & Inspection
3.3.1 The RFC is to be checked and inspected by the field service representative from the OEM to confirm proper installation.
3.3.2 The RFC is to be started-up by the field service representative from the OEM to confirm proper operation. The OEM representative should provide commissioning, training, etc. if requested by the customer.