OPERATION

THEORY OF OPERATION

When SELL mode is selected from the SET GRID USAGE menu item located under the INVERTER SETUP (9) menu heading in the SETUP MENU, the inverter will move any excess power not required to charge the batteries into the utility grid.

In SELL mode, the inverter can be thought of as a battery charger that is able to operate in either direction

-it can send excess power from the battery back into the utility grid instead of drawing power from the utility to charge the battery. To regulate the battery charging process, the inverter takes DC power from the solar array and converts it to AC power that supplies other AC loads through the utility grid. The inverter is more accurately described as a utility interactive battery charger. This means that the inverter will control battery voltage whenever utility power is connected and available. If a utility outage occurs, the inverter can not control the battery voltage. Some external control must be provided by the system to prevent damaging the battery as the solar array tries to overcharge the battery.

In a solar array configuration, a charge controller is not needed when the inverter is operational in SELL mode and utility is connected. If the inverter was turned off, or utility power was to fail, the batteries could quickly be over-charged. One of the inverter’s voltage controlled relays can be used to protect the batteries in case of utility failure. It would be programmed to open an additional external relay that controls the solar panels at a battery voltage above the battery charger’s BULK VOLTS DC setting. Please see the OVERVOLTAGE PROTECTION FOR THE BATTERY section on page 89 for more information.

UTILITY INTERACTIVE ISLANDING PROTECTION

In utility interactive mode, the inverter is capable of detecting several types of failures.

•Grid shorted - Normally, when the utility power fails, the inverter momentarily tries to power the entire neighborhood. This condition looks like a short circuit to the inverter and causes it to reach the overcurrent protection setting and shuts off. It then opens its internal relay and disconnects from the utility grid. This protective system operates instantly.

•Grid open - The inverter can tell when there is no current being delivered to the grid and it will disconnect. This is used when a disconnect switch is opened or the power line which feeds the installation is cut. This protective system operates instantly.

•Islanding - This occurs when the grid has failed and the "neighborhood" that the inverter is powering requires a power level that the inverter can supply. This condition is called “islanding”. The islanding detection circuit checks grid condition on each cycle. The inverter watches the utility grid and waits for it to rise a couple of volts before it begins to invert again. This is done on each cycle when SELL mode is activated. Typically, disconnect is achieved in a few cycles after the utility has failed. If a large electric motor is connected, it may provide enough generator capacity that the inverter thinks the grid is still connected. This can fool this protective system. Two additional protective systems are provided to then handle this condition, over/under frequency and over/under voltage detection.

•Over/Under Frequency - Since the inverter is locked onto the frequency of the utility grid, the frequency of the islanding system will drift out of regulation in a short amount of time during an islanding condition. This protective system may require a couple of seconds to respond. The settings are 58 and 62 Hertz for 60 Hertz models (48 and 52 Hertz for 50-Hertz models) and are not adjustable.

•Over/Under Voltage - Since the inverter does not try to regulate the voltage of the utility grid while selling power into it, the AC voltage will drift out of regulation in a short amount of time during an islanding condition. This protective system may require a couple of seconds to respond. The default settings are 108 VAC as the lower limit and 132 VAC as the upper limit. These settings are adjustable.

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84

2001 Xantrex Technology, Inc.

Telephone: 360/435-8826

SW Series Inverter/Charger

5916 - 195th Street N. E.

Fax: 360/435-2229

Part No. 2031-5

Arlington, WA 98223

www.traceengineering.com

Rev. C: February 2001

Page 91 Page 93
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Xantrex Technology SW Series owner manual Theory of Operation, Utility Interactive Islanding Protection
Page 91 Page 93

SW Series specifications

Xantrex Technology has established itself as a leader in innovative power solutions, and its SW Series inverters epitomizes this commitment to quality and efficiency. Designed for both standalone and grid-tied applications, the SW Series offers versatile power management for a range of residential and commercial needs.

At the heart of the SW Series is its advanced pure sine wave output, ensuring clean and reliable electricity suitable for sensitive electronics. This feature makes it an excellent choice for applications such as solar energy systems, where it provides high-quality power for a variety of devices, from household appliances to complex machinery.

One of the key characteristics of the SW Series is its modular design, which allows for easy installation and scalability. This modularity enables users to expand their power system as their energy needs grow, making it an ideal choice for both small and large installations. The inverters come equipped with a user-friendly interface, providing clear information on system performance, battery status, and more, ensuring that users can effectively monitor and manage their energy consumption.

The SW Series inverters also incorporate cutting-edge technology, such as the patented Power Factor Correction (PFC) feature, which optimizes energy efficiency by reducing harmonic distortion. This translates into less wasted electricity and lower energy costs, making it an environmentally friendly option for users looking to reduce their carbon footprint.

Another notable feature of the SW Series is its ability to operate in extreme conditions. Built with robust components and advanced thermal management systems, these inverters can withstand a wide range of temperatures and environmental challenges, ensuring reliable performance in various settings. This durability makes them suitable for off-grid applications, including remote cabins, RVs, and boats.

Furthermore, the SW Series supports a variety of battery types, including lithium-ion, AGM, and gel batteries, offering flexibility for users to choose the best energy storage solution for their needs. The sophisticated battery management system ensures optimal charging and discharging, prolonging the lifespan of the batteries and enhancing the overall efficiency of the power system.

In summary, Xantrex Technology's SW Series inverters stand out for their pure sine wave output, modular design, energy efficiency features, and robust performance in challenging conditions. With their versatility and advanced technology, they cater to the evolving needs of today’s power consumers, making them a compelling choice in the modern energy landscape.
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