Series SFC3 Guideform Specification


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 a static solid-state frequency converter system. This specification describes a three phase static frequency converter system. 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 static frequency converter system being offered. The static frequency converter hereafter shall be referred to as the "SFC".

1.2 Furnished with Equipment:

  • Factory Test Report
  • Protective Packaging
  • Installation Drawings
  • O&M Manual
  • Warranty Statement
1.3 Document & 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 Descriptions:

The SFC shall be a static solid-state type converter with a recreated true sinusoidal output, regulated phase/voltage relationship output. It shall provide the required voltage and frequency output, while also providing sufficient protection to the SFC system itself, as well as, any downstream power systems.

The SFC shall consist of modular construction solid-state components for 50Hz, 60Hz, or 400Hz conversion and ancillary control devices. The frequency converter shall be a standard product of the manufacturer and shall be the manufacturer's latest design that complies with the specification requirements hereafter. The unit shall have a calculated mean time between failure (MTBF) exceeding 24,000 hours as calculated when the converter is provided with yearly factory authorized service and maintenance.

The SFC shall be a single system rated to supply the full load as specified herein. A (N+X) paralleled SFC system shall be utilized for accomplishing redundancy, or for building power as required for the application. A redundant SFC system shall have each module rated to supply full load as specified. A paralleled SFC system 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 SFC. The system's output shall by connected to the critical load within the specified voltage and frequency range.

1.5.2 Input Power Disturbance:
The SFC may drop off line when a disturbance to the normal AC power supply falls outside of tolerance. Once the input power has been restored, the SFC will automatically restart and resume operation.

1.5.3 Output Power Disturbance:
If a disturbance to the downstream equipment being powered by the SFC is encountered the SFC system will continue to supply conditioned AC power to the load. If the downstream disturbance could possibly short circuit the output of the SFC then the SFC will automatically shut down in order to protect its critical components. The SFC will not continue operation until the manual restart is engaged.

1.6 Quality Assurance:

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.

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 procedures shall include a check of controls and indicators after installation of the equipment.

Storage, Handling, & Delivery: The equipment shall be shipped on a wooden pallet suitable for forklift handling.  The equipment shall be covered with plastic sheeting to prevent dust and dirt from entering the unit during shipment. For international shipments, 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 SFC 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 Requirements
  • Final Test Report Copy
1.8 Warranty:
The manufacturer shall state his 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:

The SFC system will be sized to handle any application up to 2,000kVA.

2.2 SFC Input:

2.2.1 Input Voltage/Frequency:
208, 440, 460, 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) configurations.

2.2.2 Voltage Operating Tolerance:
+15% to -20% of Nominal.

2.2.3 Input Current Distortion:
For units 120kVA and greater the maximum current distrotion is 15% THD at nominal input voltage while providing full rated output power. For units 80kVA and below the maximum current distortion is 33% THD at nominal input voltage while providing full rated output power.

2.2.4 Starting Inrush:
When the SFC is turned on and after the first half cycle, the inrush current shall not exceed 100% of the rated full load current. A "soft start" power walk-in circuit shall be used so the rectifier ramps up to full load.

2.2.5 Power Factor:
Between 0.8 and unity of steady state line and load variations from half load to full load as specified herein.

2.2.6 Electromagnetic Interference (EMI):
Provide units that are tested and meet FCC Class A regulations for radiated emissions.

2.2.7 Neutral Currents:
Shall not exceed 2% of any individuals phase current at no load and at full load.

2.3 SFC 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 and 200/115 and 208/120 Volts at 400Hz. These three phase input voltages are available in 3-wire (DELTA) or 4-wire (WYE) configurations. The phase rotation of the output voltage shall be clockwise sequence of A-B-C.

2.3.2 Voltage Regulation:
1% Steady state.

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

2.3.4 Frequency:
50Hz, 60Hz, or 400Hz.

2.3.5 Frequency Stability:
___Hz within plus or minus 2% of nominal for all operating conditions, including maximum and minimum specified input voltages, ambient temperature, and relative humidity. The frequency regulation shall be independent of load changes.

2.3.6 Efficiency:
The SFC shall have a minimum efficiency of 91% at nominal voltage and full load.

2.3.7 Power Factor:
Output power rating shall be 0.8 power factor lagging.

2.3.8 Load Range:
Operate into a non-linear load with a maximum crest factor for each phase current of 2.0. The crest factor is the ratio of the peak value to the RMS value under steady state conditions. The applied peak load current shall not exceed the maximum peak rated current of the SFC. The maximum peak rated current is defined as the full load RMS current times 1.414.

2.3.9 No Load Input Losses:
The SFC shall have no-load input losses no greater than 10% of the output kVA power rating at nominal input voltages.

2.3.10 Phase Angle Regulation:
Displacement angle between adjacent voltage phases shall be 120°  plus or minus 2°  with balanced load and plus or minus 4°  with three phases 15% unbalanced load. A 15% unbalanced load is defined as:
  • Phase A at full rated single phase load.
  • Phase B at 85% of Phase A.
  • Phase C at 85% of Phase A.
2.3.11 Output THD:
For a balanced linear load the THD not to exceed 3% line-to-line. Maximum single harmonic distortion not to exceed 2% of the fundamental at the nominal voltage.

2.3.12 Amplitude Modulation:
Shall not exceed 2% no load to full load, measured line to neutral.

2.3.13 Short Circuit:
When a bolted line-to-line fault, or  a bolted three phase fault is applied to the unit, unit shall be capable of sustaining the short circuit current without damage until the protective device or electronic device interrupts the fault.

2.3.14 Transient Recovery:
Operate at steady state conditions at 75% rated load. Apply a 15 percent load change, as an added load then as a dropped load. Measure and record recovery time and output voltage deviation limits. Provide recordings or display of output voltage during the transient recovery test.

2.3.15 Acoustical Noise:
Operate at no load, 50% and 100% of full load. Measure continuous steady sound pressure level 5 feet horizontally from the center of each side of the SFC at a point 5 feet above the floor. Noise level shall be less than 69dB.

2.3.16 Overload Capacity:
Satisfactory overload/over current operating time is based on no more than one overload in any (4) consecutive hours of operation. The SFC should be able to facilitate the following overload scenarios: 110% (Continuous), 125% (5 Minutes), and 150% (1 Minute).

2.4 Environmental:

The equipment shall be suitable for installation indoors (Altitude 0 to 12,000 meters or 0 to 4,000 feet) with ambient temperatures 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% to 95% non-condensing.

2.4.2 Site Conditions:
  • Ambient: 0° to 40°C (32° to 104°F) with 50°C and 55°C (Optional).
  • Humidity: 0% to 95% Non-condensing.
  • Audible Noise: 69dB NEMA 1. Lower noise levels (Optional).
  • Construction: Suitable for Indoor Applications. Outdoor enclosures (Optional).
  • Service Factor: Continuous duty, 24-hour service.
2.5 Physical Characteristics:

2.5.1 Rectifier:
The SFC rectifier shall be a phase controlled rectifier design and utilize Silicon Controlled Rectifier (SCR) thyristors. The rectifier unit shall provide direct current to the DC bus for the inverter. The rectifier shall have sufficient capacity to support a fully loaded inverter and have a minimum efficiency of 98%.

2.5.2 Input Protective Device:
Rectifier unit shall be provided with input protective devices consisting of an alternating current (AC) input circuit breaker. The protective device shall be capable of shunt tripping.

2.5.3 Inverter:
The output shall be derived from a Pulse Width Modulation (PWM) variable frequency and variable pulse width, transistorized-type inverter design and utilize insulated gate bipolar transistors (IGBTs). The inverter shall be capable of providing the specified precise output characteristics during continuous operation.

2.5.4 Output Protective Device:
The output protective device shall be capable of shunt tripping and shall have a sufficient interrupting capacity as specified.

2.5.5 Internal Protection:
The SFC module shall be self-protected against over current, sudden changes in output load and short circuits at the output terminals. The SFC shall have built-in protection against permanent damage to itself and the connected load for predictable types of failure within itself and the connected load.

2.5.6 Microprocessor Controlled Logic:
All SFC control operations are executed through the use of microprocessor controlled logic. The microprocessor's firmware has control over all the operations and parameters eliminating the need for most manual adjustments and potentiometers.

2.5.7 Display & Controls:
The SFC shall be provided with a control/indicator panel. The panel shall be on the front of the SFC module. Controls, meters, alarm, and indicators for operation of the SFC shall be on this panel, and the following functions shall be monitored and displayed:
  • Input Voltage (Phase-to-Phase)
  • Input Current
  • Input Frequency
  • Output Voltage (Phase-to-Phase or Phase-to-Neutral)
  • Output Current
  • Output Frequency
  • Cabinet Temperature
2.5.8 Alarm Indicators:
The SFC shall have indicators for the following alarm items. Any one of these conditions shall turn on an audible alarm and the appropriate summary indicator. Each new alarm shall register without affecting the previous alarm. The SFC will reflect the following alarm scenarios:
  • Input AC Power Source Failure
  • Overload
  • Overload Shutdown
  • System Over Temperature
  • Inverter Fault
  • Rectifier Fault
  • Emergency Stop Condition
  • Inverter Output Over Voltage
  • Inverter Output Under Voltage
2.5.9 Protective Controls:
The SFC shall be built with the following protective controls:
  • Input Under Voltage
  • Input Over Voltage
  • Phase Rotation Error
  • Loss of Input Power
  • Lockable Cabinet Door
  • Output Over Voltage
  • Output Under Voltage
  • Output Overload
2.6 Construction:

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 tied securely together.

2.6.2 Design:
The system shall use components of adequate rating to provide an expected service life of ten (10) years continuous duty and five (5) 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 static solid-state frequency converter systems and other power quality systems.

2.6.4 Maintainability:
No regular maintenance service operations are required, under nominal environment conditions, 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 ensure 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:
Contaminants such a 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 TCP/IP Over Ethernet Communication:
The SFC will be built with RS-485 communications, which will allow real time system status, alarm indication, system measurements, and all historical information to be remotely accessed via a SNMP card TCP/IP Ethernet protocol connected directly to a HTTP server or LAN network.

2.7.2 Outdoor Rated Enclosures:
The SFC will be built to endure the harshest outdoor environments - sand, snow, rain, salt, etc. The enclosures will be built to NEMA 3, 3R, 4, 4X, 12...standards. For large systems (400kVA+) or "turn-key" applications the SFC can be built into an ISO container allowing for easy transportation, installation, and maintenance.


3.1 Manufacturing:

The manufacturer shall design, build, test, and arrange for shipment of the SFC if requeted by the customer.

The manufacturer shall prepare and deliver the required drawings and manuals with the equipment.

3.2 Site Preparation:

The owner shall prepare their site for installation of the equipment.

The owner shall arrange for local electricians to install the equipment.

The SFC shall be installed in accordance with local codes and the OEM's recommendations.

3.3 Field Service Start-up & Inspection:

The SFC is to be checked and inspected by the field service representative from the OEM to confirm proper installation.

The SFC 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.