What is a flywheel power system?

A flywheel power system is a “mechanical battery” that stores energy kinetically in the form of a rotating mass. This energy is immediately convertible to DC power. Like a lead-acid battery bank, a flywheel power system connects to the DC bus of a UPS, charging from the bus and returning power whenever the bus voltage droops below a programmable threshold. It can supplement or completely eliminate the need for lead-acid batteries in UPS applications by riding-through short duration power quality events and brief outages or until your genset comes on line. When used in conjunction with UPS batteries, a flywheel serves as the first line of defense, isolating the redundant battery bank(s) from all cycling events.

What is the GTX?

The GTX (Voltage Support Solution) is an advanced DC flywheel power system designed and manufactured by Pentadyne Power Corporation in Los Angeles. The GTX instantly supplies short-term power to the UPS inverter until utility power is restored or until an alternate power source (such as a backup generator) is available.

Pentadyne’s GTX is compatible with several of the world’s leading brands of uninterruptible power supply (UPS) systems, and can also be used as a supporting voltage source for adjustable/variable speed drives as well as other industrial DC applications.

How does the Pentadyne flywheel work?

Why use a flywheel instead of lead-acid batteries?

Compared to batteries, the Pentadyne GTX has higher reliability, vastly lower cost of ownership, near-zero maintenance, 99.998% uptime availability, much longer useful life, accurate state-of-charge monitoring, no runtime degradation over thousands of deep cycles, no health & safety hazards, insensitivity to temperature fluctuations and environmentally responsible.

In what applications are flywheels used?

The GTX is primarily used to replace lead-acid batteries used in continuous power quality systems. The GTX can also be integrated with adjustable/variable speed drives for protection against voltage sags and brief power disturbances.

Pentadyne focuses primarily on power quality applications and on emerging applications such as energy recycling.

How are flywheels used in UPS applications?

Used as a battery replacement or supplement, the Pentadyne GTX improves UPS reliability and reduces lifecycle cost:

• Short-duration ride-through
  Integrated into a UPS system without a generator, the Pentadyne GTX can provide protection against 99% of all power disturbances (the Electric Power Research Institute–EPRI—reports that only 1% of all outages are longer than 10 seconds).
• Ride-through to generator
  The Pentadyne GTX provides ride-through time to bridge the time gap until the UPS' standby generator(s) come online for continuous power during long-term grid outages.
• Battery life extension/energy storage redundancy
  In parallel with batteries, the Pentadyne GTX provides battery protection by being the first line of defense against short-duration outages. For longer duration events, the Pentadyne system bridges the time gap until the backup generator can accept a gradual handoff of the load. This isolates the battery banks from all cycling events, making them redundant and preserving battery capacity for longer life.

What are the key benefits of the GTX?

• Higher UPS reliability
• Vastly lower operating cost
• Reduced or eliminated fire and chemical hazards common to batteries
• Reduced space allocation for energy storage
• Reduced or eliminated need for temperature-controlled space utilization
• Reduced or eliminated environmental and personnel safety issues

Who uses the GTX?

The GTX provides high quality, reliable power for power quality sensitive customers including data centers, corporate IT, hospitals, industrial plants, broadcast facilities, laboratories, financial service organizations, manufacturers and military applications.

Can the GTX retrofit into existing UPS systems?

Yes, the GTX integrates with the world’s leading brands of UPS systems.

How can I buy a GTX?

The Pentadyne GTX is available through our primary distribution partners Liebert/Emerson Network Power, Toshiba, EHWA Technologies and Socomec. Government/military customers have the option of factory-direct configuration, sales and service.

What are the standard features of the GTX?

• High reliability backed by the industry's longest warranty: 5 years
• Very infrequent minor maintenance
• >20 design life
• Environmentally friendly
• High power density/small footprint
• Very high electrical efficiency (99.85%)
• Microprocessor based self-diagnostics and maintenance
• Simple to operate, menu-driven LCD control panel
• Fast recharge capability of <15 seconds (UPS limited)
• Very low energy consumption: one-tenth that of competing products
• Soft-start UPS integration
• Programmable voltage & current settings
• Near silent operation
• Cabinet with casters for quick and easy roll-into-place setup
• Lightweight: no special floor requirement
• Front serviceable as well as top and side entry
• Compatibility tested with the world’s leading UPS brands
• Paralleling capability (no additional hardware or software required)
• N+1 configurable (no additional hardware or software required)
• Zone 4 seismic rating
• Made in USA

What makes the GTX superior to other commercially available flywheels?

The superiority of the Pentadyne GTX over other commercially available flywheel systems is clear. It is priced comparable in cost/kW, but is more compact, has higher availability and is vastly lower in cost to operate and maintain. This is mainly due to the fact that there is there is no bearing maintenance or replacement; and that there is no vacuum pump maintenance or replacement. The GTX has the:

• Highest energy efficiency (>99.85%)
• Lowest standby power draw (just 300 watts)
• Lowest heat dissipation
• Smallest footprint
• Lightest weight
• Quietest operation (45 dBA @ 1 meter) and
• Easiest and fastest installation

What is the design life of the GTX?

The GTX is designed to have a greater than 20 year life in a UPS application before a recommended factory overhaul.

What about operation during an earthquake?

Pentadyne’s patented magnetic levitation system is designed to compensate for any external vibrations, and the system is rated for seismic zone 4 (we make them in California, after all).

What is the warranty on a GTX?

The Pentadyne GTX is backed by a solid 5-year limited warranty. Warranty service and extended service contacts are available directly or through our distribution partners: Liebert/Emerson Network Power, Toshiba, EHWA Technologies and Socomec.

To what standards are the GTX units designed and manufactured?

Pentadyne is an ISO-9001:2008 certified company. Its GTX product is UL-certified to all applicable Underwriters Laboratory standards:

• UL 508, Standard for Safety for Electrical Industrial Control Equipment
• UL 1004, Standard for Safety for Electric Motors
• UL 1248, Standard for Safety for Engine-Generator Assemblies

The following Canadian Standards as determined by UL:

• CSA-C22.2 No. 100-04, "Motors and Generators"
• CSA-C22.2 No. 14-95, "Industrial Control Equipment"

The VSS+dc also complies with the applicable sections of the requirements of the:

• National Fire Protection Association (NFPA)/National Electric Code (NEC);
• National Electrical Manufacturer's Association (NEMA);
• Occupational Safety & Health Administration (OSHA).

In Europe , the GTX is CE marked to meet the applicable requirements of these European Directives:

• “Low Voltage Directive” 73/23/EEC and its amendments by the directive 93/68/EEC;
• “Machinery Directive” 98/037/EEC and its amendments by the directive 98/79/EEC;
• IEC/EN 60439-1:1999 “Low-voltage switchgear and control gear assemblies Part 1: Type-tested and partially type-tested assemblies”;
• IEC/EN 60204-1:1997 “Safety of machinery – Electrical equipment of machines Part 1: General requirements”;
• EN 1127-1:1997 “Explosive atmospheres: Explosion prevention and protection Part 1: Basic concepts and methodology”
• Machinery Directive Annex 1 “Essential Health and Safety Requirements Relating to the Design and Construction of Machinery and Safety Components”;
• “Electromagnetic Compatibility (EMC) Directive” 89/336/EEC and its amendments by the directives 92/31/EEC and 93/68/EEC.

Any safety concerns?

Safety is paramount in the design of the GTX. Unlike a large metal flywheel weighing hundreds of pounds, the 25 pound Pentadyne flywheel will not fragment. In descructive tests, the carbon-fiber flywheel simply unravels into fibers and dust adhering to the inner housing like cotton candy. More than 30 different such tests were performed at Pentadyne to ensure that no part of the spinning mass could ever escape the housing.

The rotating mass is contained within two housings: a 2-inch-thick steel inner housing that surrounds the rotating group, and a separate steel outer housing. The inner housing is over-engineered to handle the pressure load and contain all the flywheel elements in the unlikely event of a rotating group failure. The cavity between the two housings is filled with a viscous non-toxic fluid that acts as a coolant during normal operation and as a hydrodynamic buffer if a failure such as this were ever able to occur. The inner housing is attached to the outer housing via break-away flanges so that the inner housing will shear free and rotate briefly within the cooling fluid that now acts as a hydraulic brake. This allows the energy from the flywheel to be dissipated safely within a few seconds, ensuring that no significant torque is transferred to the cabinet.

Underwriters Laboratories (UL) and TUV (German certification body) conducted thorough analyses of Pentadyne's patented safety system. Both certification bodies granted their seal of approval to the VSS+dc which is UL Listed and CE Marked.

How much energy can a single GTX unit provide?

On a 510 VDC or greater UPS bus, the GTX is designed to provide a continuous 200 kW for 12 seconds (or longer at lower outputs). UPS systems are usually loaded to about half their nameplate rating and have a 0.8 power factor, so one unit on a 400-kVA UPS at 50% loading will provide more than 15 seconds of runtime to bridge to a backup generator (which can usually assume a gradual transfer of the load 5-6 seconds after starting). For higher power requirements, longer durations and/or redundancy, multiple GTX units can be run in parallel without any communications gear. See the chart on our specifications page for a runtime guide or contact us and we'll work out the specifics for your particular application.

What is the energy efficiency of the GTX?

Average power consumption (standby loss) is less than 250 watts (i.e. 0.13% of 200 kW). Conventional flywheel systems use much more: 2,000 to 3,500 watts. This poor energy efficiency alone will increase utility bills by thousands of dollars per year for each flywheel deployed. The high efficiency of the GTX is due to Pentadyne's technological choices including:

• operating the flywheel system within a high vacuum
• using zero-drag magnetic levitation
• high-efficiency synchronous reluctance motor-generator
• having a liquid coolant system that activates only at higher temperatures (i.e., only if the system has performed a deep discharge or several partial discharges in frequent succession).

Can I adjust the charge current?

The charge current is adjusted via the control panel on the front of the GTX. The maximum charge current in UPS applications is limited by software to 50 amps. If your UPS can make more power available to the GTX, recharge times will be reduced. We invite you to contact us for details.

What is the operating voltage range of the GTX?

The GTX has a wide operating voltage range. It is UL listed for 350 to 600 VDC, as limited by UL standards, but it can connect at voltages up to 850 VDC. The GTX is designed to provide maximum power at voltages above 510 VDC.

How long does the GTX take to recharge after a full discharge?

After a complete discharge, the GTX will be back up to full power capacity in less than 2.5 minutes at 50 A charging current with a charging voltage between 500 to 600 VDC. Recharge time following a partial discharge event is much shorter. The GTX can be recharged to full power in the same time it takes to discharge if the UPS rectifier can supply full power to the GTX while supporting the critical load. Also, if another grid disturbance occurs during the recharge process, the GTX will instantaneously support the load with its available energy.

How many GTX units can be put together in parallel?

Just like battery cabinets, you can link an unlimited number of Pentadyne systems for higher capacity/duration/redundancy. No communications gear or software is needed to parallel GTX units, it's all built-in. Multiple-unit installations are common. To date, the largest array involves 20 units at a US government data facility.

Are communication links needed for paralleling?

No, there is no need for communication link between the GTX units for parallel operation. Each unit works independently from the others: just like battery strings, only more reliable.

Is the GTX noisy?

The sound level in normal operation is barely audible: less than 45 dBA @ 1m. Competing flywheels rated at 65-70 dBA @ 1m are hundreds of times louder.

How do I know when the GTX is fully charged?

When the flywheel is at full speed, the state of charge is 100%. The state of charge is clearly displayed on the control panel lcd screen.

What is the operating temperature range the GTX?

Operating: -4°F to 122°F (-20°C to 50°C); non-operating: -4°F to 176°F (-20 to 80°C)

Does the GTX have remote monitoring capability?

Yes, Pentadyne makes Microsoft Windows-based remote control & monitoring options available to enable remote interactivity with the GTX. The GTX can be remotely accessed through a local area network, the Internet or through a phone line via an optional modem.

What is the difference between low-speed and high-speed flywheels?

Low-speed flywheels are made of steel and rotate at 7,000-8,000 rpm. Low speed flywheels have certain advantages, such as relatively simple design. Disadvantages include high weight, low power density, larger footprint, poor energy efficiency, high heat output and relatively frequent and costly maintenance/availability issues.

High-speed flywheels use high-strength composite materials and magnetic levitation, which allows the rotating group to spin at much greater speeds without friction to generate far greater power density. Most operate in the 25,000 - 60,000 rpm range. While high-speed flywheels are more difficult to design, the finished product has the same or lower cost per kilowatt as low speed models, but offer distinct advantages, such as high power density, compact design, very high energy efficiency, very low heat output, extremely high uptime availability and exceptionally infrequent low-cost maintenance.

What are the key technologies used in the GTX?

The Pentadyne GTX includes several key patented technologies:

• High speed carbon fiber flywheel
• Five-axis active magnetic levitation
• Integrated molecular vacuum sleeve
• Synchronous reluctance motor-generator
• None of these components ever require maintenance.

What is the warranty on a GTX?

The Pentadyne VSS+dc is backed by a 5-year standard limited warranty. Warranty service and extended service contacts are available directly or through our distribution partners: Liebert/Emerson Network Power, Toshiba, EHWA Technologies and Socomec.

What maintenance is required on the GTX?

Very minimal maintenance is needed. The only regularly scheduled downtime maintenance involves a low-cost capacitor replacement at six-year intervals. This service takes less than an hour.
That's it!

If ordered with the optional air filter, ambient conditions will determine the frequency of replacement. Replacement of the filter does not require any downtime.

How does this compare with other flywheels?

Pentadyne has solved the significant maintenance problems of traditional flywheels by removing all maintenance and replacement requirements associated with mechanical bearings, pumps, oil changes, etc. Those older technology systems require extensive and costly maintenance intervals that entail significant downtime.

Is the GTX front serviceable?

Yes. The system was designed so that all component modules are easily accessible from the front of the unit.

What type of power conversion technology is used in the GTX?

The Pentadyne GTX uses a bi-directional power converter to either extract or supply energy to the DC bus. The system uses high-power IGBTs (insulated gate bipolar transistors) and PWM (pulse width modulation) technology.

What is the nominal operating speed of the flywheel?

The rotating group spins at speeds at 25,000 (fully discharged) to 52,000 (fully charged) rpm.

Is there any vibration?

No, the system is entirely vibration free. Moreover, its patented magnetic levitation system is designed to compensate for any external vibrations, and the system is rated for seismic zone 4 (we make them in California, after all).

Does the GTX use mechanical bearings?

No, that's one of the major advantages of the GTX over other flywheel power systems. The GTX uses a patented five-axis magnetic levitation system. It consists of electromagnets (2 radial “X”, 2 radial “Y”, 1 axial “Z”) that levitate the rotating group so there is no mechanical contact during operation. This eliminates the wear and energy inefficiency common to all mechanical bearing flywheel systems.

The patented magnetic levitation system is completely maintenance-free for the life of the GTX (>20 years).

Does the GTX have a vacuum pump?

No. The design of the vacuum chamber (where the flywheel rotates) is factory sealed. At the top of the rotating group shaft is a maintenance-free patented molecular vacuum sleeve that maintains a near-total vacuum, a pressure level nearly a million times lower than atmospheric pressure. This eliminates aerodynamic drag for maximum energy efficiency. The sleeve discharge is stored in absorbers located in an attached evacuated housing. This configuration eliminates the need for the mechanical vacuum pumps used on other flywheels that require electric power as well as maintenance every 6-12 months and costly replacement every 3-4 years.

What type of motor-generator is used?

Pentadyne uses a synchronous reluctance motor-generator, which does not require the use of permanent magnets. This type of motor-generator is extremely energy efficient and one of the primary reasons that the GTX has one-tenth the electricity consumption of competing products. Unlike permanent magnet type motor-generators that are sensitive to heat (especially in a vacuum), performance of our synchronous reluctance motor-generator does not degrade over time.

How easy is it to install the GTX?

The GTX is designed to “plug and play.” The lightweight system (1,300 lb/590 kg) can easily be moved with a forklift, a hand pallet lift, or simply rolled into place on its built-in casters. No concrete padding or other special flooring requirements are needed. The system can simply be leveled and bolted into place on any common flooring, including raised flooring.

Does the GTX need to be secured to the floor?

Yes, the safety system relies on floor mounting, since gyroscopic force during a discharge could cause the system to move. So the GTX is simply bolted to the floor using four small anchor bolts. These anchors are very easy to install. The system is designed for front access service, so there is never a need to unbolt the system for maintenance.

Does the floor need to be perfectly level?

No, the GTX is supplied with leveling feet so that uneven floors can be accommodated. A bubble level is located at the top of the flywheel for leveling accuracy.

Can the GTX be mounted on a wooden or raised floor?

Yes, a mounting kit is available for these installations. There is no special floor requirement for installation.

What are the dimensions?

Width, depth and height are: 25 x 33 x 71 in (63 x 83 x 180 cm). These dimensions enable the system to fit easily through any door opening.

What is the footprint?

The GTX has a small footprint: 5.7 ft²/0.5 m².

How heavy is it?

The GTX weighs 1,300 lb/590 kg. This is about ¼ the weight of a comparable battery cabinet.

Is AC power required for the GTX operation?

AC power is used as a backup source and for initial parameter selection during start-up.

What voltage level is required for the AC power input?

Standard wall socket 120 or 230 VAC at 50 or 60 Hz.

How do I connect the GTX to a UPS system?

The GTX connects just like a battery cabinet: to the two UPS DC bus terminals and the ground connection.

The GTX has been integrated with UPS systems from all leading manufacturers via optional interconnection kits.

Is the start-up of the GTX a specialized task?

We recommend that a factory-trained Pentadyne-Certified Technician commission each new unit to ensure proper operation and to validate the system's 5-year warranty.