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Frequently Asked Questions (FAQs)

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General Industrial Generator Questions

What size gensets are available and what are my fuel options?

  • Diesel models range from 10 kW to 600 kW.
  • Gaseous models range from 18 kW to 300 kW.
  • A Bi-Fuel option is available on selected models.

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Can Generac gensets be integrated with my building management system?

The PowerManager® G-100 features integrated PLC functions and numerous I/Os that make it easy to customize controls and link directly with facilities management systems. Two Modbus RS 485 ports accommodate controller-to-annunciator or building management system communications.

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Can I monitor the system's performance from a remote location?

An optional Ethernet modem with an RS232 port provides remote computer interface using our GenLink® software. Connected PCs display continuously updated information about the generator's operating condition. Input values and operational parameters can be easily viewed using point-and-click menus and status screens. Valuable information such as generator usage data, alarm history and predictive maintenance reminders are easily accessible.

If an alarm occurs, it is immediately displayed on connected remote computers, and the PowerManager control panel can be programmed to immediately send out a call to both the user's and your Generac dealer's pagers or cell phones. The dealer can use GenLink to remotely diagnose the problem, modify parameters to minimize the impact and immediately dispatch a service truck with the necessary parts to quickly correct the situation.

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How many automatic transfer switches can be used in a single system?

There is no limit on the number of open transition, closed transition or bypass isolation switches that can be used within a system. Only one soft load switch can be used.

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Can the PowerManager G-100 controller interface with third party transfer switches?

Yes, provided that the switches have a two-wire start, and can be inhibited by the controller from switching to the emergency position until adequate generator power has come onto the generator bus.

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If I purchase a single standby generator, can I add units later and convert to a Modular Power System?

No. The G-100 controller will not interface with the control system for a Modular Power System. If you think you might need to expand capacity in the future, you should purchase a single MPS genset with the PowerManager G-200 controller.

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Bi-Fuel Generator Questions

What does Bi-Fuel™ refer to on standby generators?

Bi-Fuel is the simultaneous use of two different fuels to power the engine on a standby generator set. For Bi-Fuel operation, Generac uses a mixture of diesel fuel and natural gas (NG) in a diesel engine.

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Is this different than dual-fuel?

Unfortunately, there is no clear answer. Both bi-fuel and dual-fuel are used within the industry to describe the concept of simultaneous combustion. In addition, both terms have also been applied to redundant fuel supplies where a secondary fuel is used only after the primary fuel is depleted or intentionally switched off. Therefore, it is important to understand how the terms are being used when comparing products. Generac uses the term Bi-Fuel for the simultaneous combustion of both fuels, and dual-fuel to describe a system in which liquid propane vapor serves as a backup fuel source in a natural gas system. This system is available as an option on a number of our gaseous fueled generators.

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Is the Bi-Fuel concept a new technology?

No. Bi-Fuel has been around since the early 1900's. However, early designs lacked adequate controls to make it very effective. Since that time, much development has occurred and control technology has advanced to make Bi-Fuel operation efficient and economical. Generac has developed a microprocessor-based control system that meets the challenge of maintaining an optimal balance of diesel and NG across the power range of the engine.

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How does the Generac Bi-Fuel system work?

Generac uses relatively low cost, high volume diesel truck engines that have been well proven in demanding trucking applications. The engine starts on 100% diesel fuel. As soon as the coolant reaches a minimum temperature and the generator starts to accept load, natural gas is metered into the combustion air stream just before the turbocharger. As compression occurs, the diesel fuel ignites normally and provides the spark required to ignite the natural gas.

As load is applied, the amount of natural gas is increased and the amount of diesel fuel is decreased. We have conducted comprehensive testing and fuel ratio mapping to ensure safe, reliable operation under all combinations of load and temperature. Our PowerManager® control system continually monitors factors such as coolant temperature, intake manifold temperature and pressure, kW load and engine speed. The fuel mixture is instantly adjusted as needed. Under typical conditions, the operating fuel mixture will consist of at least 70% natural gas.

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What are the benefits of Bi-Fuel?

  • Dramatically extended run times with available on-site supply of diesel fuel
  • Lower capital cost per kilowatt (kW) than spark-ignited engines
  • Improved reliability with redundant fuel supply
  • Reduced diesel fuel storage
  • Reduced fuel maintenance
  • Lower exhaust emissions than diesel engines

Is Bi-Fuel operation detrimental to the diesel engine?

No. In fact, the cleaner burning characteristics of NG result in less contamination of lubricating oil and reduced engine wear. In addition, peak cylinder pressures and exhaust temperatures, the key factors in engine wear, are lower during Bi-Fuel combustion than during diesel-only operation.

The PowerManager controller protects the engine by sensing the signature vibration signal created as conditions approach pre-ignition and immediately reduces the supply of natural gas before pre-ignition can occur. If the condition persists, natural gas is shut off, operation continues on 100% diesel fuel and an alert is issued. Extensive testing has shown that a Generac Bi-Fuel engine will have a longer operating life with extended service intervals and reduced maintenance costs than a standard diesel engine.

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What happens if natural gas pressure drops or the supply is cut off?

The system will automatically and seamlessly switch to 100% diesel operation with no loss of power during the transition. It's important to remember however, that the system cannot run on 100% natural gas because the ignition of the diesel fuel provides the spark that ignites the natural gas.

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Can I monitor the amount of natural gas being used by the engine?

Yes. Our GenLink® software allows you to monitor all aspects of generator performance, either locally or remotely. GenLink can display natural gas flow both numerically and graphically.

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How does the transient response of the Bi-Fuel engine compare to a standard diesel engine?

The Bi-Fuel engine's transient load response is the same as a diesel engine. The standard diesel governing system is always active. During sudden load changes, diesel instantly becomes the dominant fuel so the engine will react just like a normal diesel engine. As a result, the Generac Bi-Fuel maintains the superior transient response of a diesel engine while providing the benefits of natural gas operation.

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Can Generac Bi-Fuel generators be used in prime power applications?

No. At this time Generac Bi-Fuel generators are rated for standby applications only.

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Are Generac's Bi-Fuel generators UL Listed?

Yes. As with all Generac generators, our Bi-Fuel units are UL 2200 Listed for Stationary Engine Generator Assemblies. Both UL Listing and CSA Certification are available options on these units.

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Where do I go for warranty repairs or to purchase parts?

Contact any Generac Service Dealer. To locate a dealer near you, please refer to our Dealer Locator or call 1-888-GENERAC. Our Service Dealers provide parts, service scheduled maintenance and information on Generac equipment, regardless of where it was purchased.

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Where is my generator made?

Generac generators are made in the United States. Manufactured by Generac Power Systems, Inc. in one of three manufacturing facilities in Wisconsin.

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Gemini Generator Questions

What is a Gemini system comprised of?

Two diesel 500 kW gensets in a single enclosure. Up to seven Gemini units can be paralleled for a total output of 7000 kW.

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Must all of the gensets in a system have the same kW rating?

Individual gensets with different kW ratings can be used within a single system. The only exceptions are the MQT gensets which can only be paralleled with other MQT units with the same kW rating.

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What kind of paralleling switchgear is required for an MPS system?

Generac MPS is a completely integrated system, so no additional switchgear is needed. Our PowerManager® Digital Control Platform features a 32-bit microprocessor and replaces multiple generator controllers and expensive paralleling switchgear. The PowerManager G-Series is a flexible control platform that utilizes mission-specific software that enables it to function as the controller for the individual gensets, an integrated paralleling controller and the system controller.

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How does MPS facilitate internal and external communications?

The PowerManager G-Series features integrated PLC functions and numerous I/Os that make it easy to customize controls and link directly with facilities management systems. Two Modbus RS 485 ports accommodate controller-to-generator and controller-to-annunciator or building management system communications. An integrated Ethernet modem with an RS232 port provides remote computer interface and control using our GenLink® software.

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What happens if one of the gensets does not start or is lost after transfer?

The PowerManager System G-Series System Controller has ATS permissive relays. If the loads are prioritized among two or more transfer switches, the permissive controls will not allow lower priority loads to switch to emergency power and the critical load is automatically spread among the remaining gensets. If transfer has already occurred, lower priority loads are immediately shed and the critical load is carried by the remaining gensets.

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How many automatic transfer switches can be used in a single system?

There is no limit on the number of open transition, closed transition or bypass isolation switches that can be used within a system. Only one soft load switch can be used.

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Can the G-Series System Controller interface with third party transfer switches?

Yes, provided that the switches have a two-wire start, can be mechanically held in the neutral position by the controller for load shedding and can be inhibited by the controller from switching to the emergency position until adequate generator power has come onto the generator bus.

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Do all of the gensets have to be placed together?

No. Generac MPS gensets can be separated to allow you to better utilize available space. It is possible to place some units on the ground and others on the roof, or to utilize multiple smaller spaces without affecting performance. The location of the system controller is limited to no more than 1500 feet by the RS-485 communication cable.

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Are Modular Power Systems being used in mission critical applications?

Yes, these systems are fully compliant with NEC 700 and NFPA 110. Mission critical applications represent a significant percentage of MPS installations.

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