1.1 Summary

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 an Synchronous Motor Generator. This specification describes a three phase motor generator set to be utilized for power conditioning applications. 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 induction motor generator set being offered. The synchronous motor generator set hereafter shall be referred to as the “SMG”.

1.2 Furnished with Equipment

  1. Factory Test Report
  2. Protective Packaging
  3. Installation Drawings
  4. O&M Manual
  5. Warranty Statement

1.3 Documents & Standards

National Electrical Code, NFPA 70-2005.

IEEE C2 (1993) National Electrical Safety Code.

IEEE C62.41 (1980) Guide for Surge Voltage in Low-Voltage AC Power Circuits.

FS W-C-375 (Rev. B; Notice 1) Circuit Breakers, Molded Cases, Branch Circuit and Service.

NEMA AB 1 (1986; Rev. 1989) Molded Case Circuit Breakers and Molded Case Switches.

NEMA 250 (1985; Rev. 1988) Enclosures for Electrical Equipment (1000 Volts Maximum).

Occupational Safety & Health Act (OSHA).

Local Codes & Authorities having jurisdiction for this installation.

1.4 System Description

1.4.1 The SMG is to provide regulated AC power to critical loads under normal and abnormal conditions. The SMG shall be a rotary type with regenerated true sinusoidal, phase and voltage relationships output. There shall be no electrical connections between the utility AC input and the regenerated output to the critical loads.

1.4.2 The SMG shall include a synchronized electromechanical automatic bypass contactor to switch the critical load without interruption from the SMG to the alternate AC source in the base of a fault situation. Additionally, the SMG and all associated controls shall provide a means of electromechanically isolating and filtering disturbances in the AC power source from the protected load.

1.4.3 Synchronous Motor – Synchronous Generator (M-G): The portion of the SMG 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 creating total electrical isolation from the input to output.

1.4.4 Automatic Bypass Contactor: The portion of the SMG that shall automatically transfer the critical loads from the generator output to the AC input source without interruption in the event of degradation of the SMG performance. The automatic bypass shall be electromechanical for complete isolation of the power paths.

1.4.5 The SMG shall be a single system rated to supply the full load as specified herein. A (N+X) paralleled system shall be utilized for accomplishing redundancy, or for building power as required for the application. A redundant SMG system shall have each module rated to supply the full load as specified. A paralleled SMG intended for building power shall be rated as specified for the requirement.

1.5 System Operation

1.5.1 Normal: Alternating Current (AC) line power shall be supplied continuously to the SMG. The generator output shall be connected to the critical load. The generator output shall also be synchronized with the alternate AC power source provided that the alternate AC power source is within the specified voltage and frequency range. During brief disturbances of normal AC input power the SMG shall supply AC power to the critical load.

1.5.2 Power Source Return: The SMG shall continue to supply AC power to the criticial load when the normal AC power source returns. This shall be an automatic function and shall cause no disturbance to the critical load.

1.5.3 Alternate Source Transfer: If the SMG senses a fault or an output out-of-tolerance condition a shut down signal shall automatically transfer the critical loads from the generator output to the alternate AC power source without an interruption of power. If the alternate AC power source is outside normal limits, then the transfer will be inhibited.

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 Submittals 

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 SMG shall be sent to the purchaser to be used in planning the installation of the system.

1.7.3 Formal Approval: If a formal submittal approval is required for the project then the following should be requested, submitted, and approved before design/construction of the IMG system commences:

  1. Equipment Installation Outline
  2. External Cabling Connection Diagram
  3. Equipment One-Line Power Diagram
  4. Equipment Elevation Drawing
  5. “Other” Site Evaluation Drawings

1.7.4 Delivery of Equipment:

  1. Operation & Maintenance Manual
  2. System Installation Procedures
  3. System Operation Procedures
  4. System Troubleshooting Instructions
  5. System Maintenance Requirements
  6. Recommended Spare Parts List
  7. Final Test Report Copy

1.8 Warranty

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 Capacity

2.1.1 The SMG system will be sized to handle any application up to 5,000kVA.

2.2 SMG Intput

2.2.1 Input Voltage/Frequency: 208, 440, 406, 480, or 600 Volts at 60Hz and 208, 380, 400, 415, or 600 Volts at 50Hz. These three phase input voltages are available in 3-wire (DELTA) or 4-wire (WYE).

2.2.2 Voltage Range: +15% to -15% of Nominal.

2.2.3 Voltage Transient Impulse: To 1500V for not more than 1 milliseconds.

2.2.4 Starting Inrush: 3X Nominal input amperage.

2.2.5 Ride-Thru (Operational): Please see “Ride-Thru Specification” for additional information.

2.3 SMG Output

2.3.1 Output Voltage/Frequency: 208, 440, 460, 480, or 600 Volts at 60Hz and 208, 380, 400, 415, or 600 Volts at 50Hz. These three phase output voltages are available in 3-wire (DELTA) and 4-wire (WYE) configurations.

2.3.2 Voltage Regulation: 0.5% Nominal output (Steady-State) and 3.0% (25% Unbalanced).

2.3.3 Recovery Time: 0.5 Seconds.

2.3.4 Voltage Adjustment: +/- 10% of Nominal.

2.3.5 Transient Voltage Regulation: +/- 8% (50 Step Load).

2.3.6 Power Factor: 0.8 Lagging.

2.3.7 Harmonics: 5% RMS (Total), 3% RMS (Single).

2.3.8 Phase Separation: 120° +/-1° (Balanced Load). 120° +/- 3° (Unbalanced Load).

2.3.9 Overload Capacity: 110% (Continuous), 125% (10 Minutes), 150% (1 Minute).

2.4 Environmental

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:

  1. Ambient: 0° to 40°C (32° to 104°F) with 50° and 55° (Optional).
  2. Humidity: 0% to 95% Non-condensing.
  3. Audible Noise: 90dB Open Frame. Lower noise levels (Optional).
  4. Construction: Suitable for indoor application. Outdoor enclosures (Optional).
  5. Bearings: Grease lubricated, Anti-friction type.
  6. Service Factor: Continuous duty, 24-hour service.

2.5 Physical Characteristics

2.6.1 System Description: The SMG set shall consist of a two bearing induction motor, reduced current motor starter, motor controls, motor input circuit interrupter, brushless two bearing synchronous generator with paralleling capability, direct connected brushless AC excited with rotating rectifiers, bolted steel coupling between the motor and generator, generator controls, generator output breaker, and a common mounting steel base with vibration isolators.

2.6.2 Controls:

  1. The controls shall be mounted in a separate floor standing cabinet.
  2. Motor Control: START switch at the SMG set that activates the reduced current motor starter.
  3. Motor Starter: Reduced current motor starting shall be accomplished by the following method. The IMG shall be equipped with a WYE DELTA Starter that reduces the initial starting inrush. For specific data please consult the factory
  4. Instruments: Metering with 2% accuracy shall be provided to monitor the following conditions – AC Input Voltage (Each line voltage with selector switch), AC Input Circuit (Each phase with selector switch), AC Output Voltage (Each line-to-line voltage with selector switch), and AC Output Current (Each phase with selector switch).

2.6.3 Voltage Adjustment Range: Output voltage control shall provide up to a +/- 10% adjustment range from nominal.

2.6.4 Fault Detectors: The SMG shall be equipped with protective devices, which shut the unit down and activate internal latched indicators. These indicators shall retrain the fault indication after the SMG set has stopped to simplify troubleshooting.

  1. Output Over Voltage
  2. Output Under Voltage
  3. Starter Overload
  4. Output Under Frequency
  5. Motor Overload
  6. Motor Over Temperature
  7. Motor Bearing Over Temperature
  8. Generator Bearing Over Temperature

2.6.5 Status Lights: Indicator lights shall indicate different conditions, including: Motor On, Load On, System Bypass, and System Fault.

2.6.6 Uninterrupted Bypass: The interior bypass will transfer the critical load from the SMG set back to the utility without interruption. The bypass can be initiated either manually by a switch or automatically by the standard fault detectors listed above. There will be no more than (+/-8%) voltage transient during bypass.

2.6.7 Cycle-On-Line: The SMG will be capable of operating the critical load equipment directly on the utility, starting the SMG, synchronizing the SMG with utility and transferring the critical load to the SMG without interrupting the operation of critical load equipment. The starting sequence will be automatic after initiation by the start switch. The cycle-on-line sequence will be automatic after closing the generator circuit breaker. The transition shall be without interruption of the critical load.

2.6.8 Emergency Power Off (EPO): This feature immediately disables power to the SMG system via a set of switchable normally closed/open dry contacts.

2.6.9 Power Outage Protector: The SMG shall be equipped with protector circuits, and in the event of a sustained power outage the breaker will be tripped when the output frequency decays to a preset level. Furthermore, the motor shall be protected from a return of utility power before the SMG has coasted to a complete stop.

 2.7 Construction

2.7.1 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.

2.7.2 Design: The SMG 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.

2.7.3 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.

2.7.4 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.

2.7.5 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.

2.7.6 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.

2.8 Optional Features

2.8.1 Two Beating, Common Shaft Design: This SMG  two bearing, common shaft design differs from the four bearing configuration in that no belts or sheaves are utilized in its internal 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.

2.8.2 PLC Based Color Touch Screen Controls:

  1. Motor Control: The START pushbutton on the IMG touch screen interface will activate the reduced current motor starter.
  2. 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.
  3. 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).
  4. Voltage Adjustment Range: Output voltage control shall provide up to a 10% adjustment range from nominal using the color touch screen HMI.
  5. Fault Detectors: The SMG 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.
  6. 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.
  7. 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.
  8. Controls: The SMG 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.
  9. Power Outage Protector: The SMG 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 SMG has coasted to a complete stop.

2.8.3 Remote Monitoring System: There are many methods that can be utilized to allow the user to interface with the SMG system giving them a wide range of monitoring and control options:

  1. Modbus: Modbus over serial line with RTU protocol. A modbus serial port is provided to remotely access the SMG modbus registers and status bits. All the IMG 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 SMG Modbus registers and status bits the same as RTU but with a TCP interface that runs n Ethernet. Please contact factory for additional information.
  2. Web Based: The web based remote monitoring/control feature puts the user at the control screen of the SMG, 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.
  3. Remote Color Touch Screen: All SMG 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.

2.8.4 Exhaust Silencer: The SMG 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 SMG assembly.

2.8.5 Sound Attenuated Enclosure: The SMG 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 SMG, 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.

2.8.6 Outdoor Rated Enclosure: The SMG 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 SMG can be built into an ISO container allowing for easy transportation, installation, and maintenance.


3.1 Manufacturing

3.1.1 The manufacturer shall design, build, and test the SMG system. If requested by the customer, the manufacturer shall arrange shipment of the SMG 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 SMG is to be checked and inspected by the field service representative from the OEM to confirm proper installation.

3.3.2 The SMG 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.