AC generators produce a different type of electrical energy from DC generators and are best suited for specific applications. Both generators look simialar and come in many different sizes and styles.
Alternating Current (AC) generators are typically used for temporary power on construction sites and emergency power when the electrical grid fails. AC generators must run at a constant speed to deliver a stable AC voltage, even if little to no load is present. AC generators are sized to handle the total connected load, overloading will shut down the system. For many people who have experience using AC generators, have noticed the reduced quality and reliability with lower priced brands as many imported AC generators are considered a disposable product.
Direct Current (DC) generator are typically found in mobile or off-grid applications. DC generators provide a seamless energy supply directly into batteries and DC power grids without special equipment. Stored energy in batteries is distributed to loads including loads through DC-AC inverters. ALTEN DC generators can be throttled back to an idle speed as batteries are being recharge, saving even more fuel fuel.
Renewable energy from the sun or wind are usually stored in batteries for later use when renewable generation is not available. Sizing renwable systems and battery storage capacity can be challenging. ALTEN DC generators eliminates the challenge or worry to "buffer" generation, storage and loads.
When DC current is needed, people unfamiliar with DC generators will often use AC generators plus complex electrical equipment when an ALTEN DC generator could have provided a more efficient, reliable power generating platform. Size is not so important when selecting a DC generator, see ALTEN sizing-guide for help.
There are, however, specific reasons when a DC generator should be used versus an AC generator. For example, the use of a DC generator is more appropriate and effecient when used to:
- Recharging critical battery systems on land or at sea, such as communication and navigation systems.
- Backup DC supply power on remote power systems, such as telecom and scada systems.
- Heavy industrial equipment used in remote locations, above or below ground.
The Advantages of a Hybrid Energy Platform
Some ALTEN DC generator models can monitor the state of charge (SOC) in battery banks to automatically start and stop battery charging. Intermittent battery charging combined with Grid power and/or renewable energy power is considered a hybrid-power platform and the amount of fossil fuel burned is greatly minimized versus an AC generator. An ALTEN hybrid-energy platform provides an efficient, reliable and sustainable power platform with the added bonus of enhanced energy security in the event any natural or man-made disasters called extended power outages.
Renewable Energy Systems and DC Generators
Often, renewable energy systems tend to be oversized to bridge any energy shortfalls during cloudy or non-windy days. The savings to purchase and install smaller solar panels, wind turbines and extra batteries would cover the cost of a ALTEN DC generator to buffer the power needs. In the big picture, it would make more sense to use ALTEN DC generators to realize greater numbers of affordable renewable energy installations, worldwide.
When Size Dosen't Matter
A DC generator can be sized smaller than an AC generator for the similar application and need only run intermittently. An AC generator must be sized to power the largest connected AC load at any one time and must run constantly, burning more fuel than a DC generator. As a result, AC generator requires considerably more maintenance and would have a shorter life cycle. For help, see sizing-guide.
Remote Monitoring
A service call to check up or make repairs to remote power systems systems can be expensive. ALTEN offers an Internet-based RMS (remote monitoring system) allowing operators to monitor, control and program the entire DC power platform from anywhere in the world.
| AC Generators | DC Generators | |
|---|---|---|
| System Connectivity | Require a high degree of engineering and equipment costs to transfer power onto an isolated section of the electrical network. | Do not require a transfer switch, energy flows seamlessly into a DC power system safely. |
| Expandability | Cannot be connected in parallel without expensive phase synchronizing equipment. | Can be easily connected in parallel to add capacity without special equipment. Polarity is the only concern. |
| Energy Quality and Stability | Any change is RPM significantly affects power output quality. Speed control devices such as governors need regular service. | Are not affected by engine speed variations and produce a constant and stable DC voltage. |
| Safety and Regulation | Are normally 120 volts and above and require special certification for safety reasons. Alternating current can be deadly and cause serious injury. | Low voltage DC generators less than 50 volts require minimal permitting and inspection by safety and regulatory authorities. |
| Sizing and Efficiency | Must be sized to power the greatest combined loads that may be connected at one time. Smaller loads may be connected a majority of the time, but the larger generator still has to run at full speed the entire time. | When charging batteries, can be sized much smaller to provide a steady charge current. Surge currents are supplied through the battery bank and act as a buffer. |
