Alternative energy glossary. (The Solar Cowboy).

Single quadrant: Power is taken from a voltage source, delivered to a load. Power does not go back to the voltage source.

Example: Current flows from the voltage source to the load, only. Current flows from a battery to a motor. The motor cannot operate as a generator, and has to coast to a stop.

Two quadrant: Power is taken from a voltage source, delivered to a load, or vice versa.

Example: Current flows in both directions. Current flows from or to a battery when connected to a DC motor that runs in only one direction. The motor can operate as a motor or generator, but the motor shaft turns in one direction. The motor can be stopped abruptly, but not reversed.

Four quadrant: Power is taken from a voltage source, delivered to a load, or vice versa, and the voltage to the load can be reversed.

Example: Current flows in both directions, and the voltage to the load can be of either polarity. Current flows from or to a battery when connected to a DC motor that runs in both directions. The motor can be stopped abruptly, and dynamically reversed.

AC/DC converter: Power is taken from a voltage source, delivered to a load. Usually the conversion is a voltage to a voltage, but can be a voltage to a current.

Example: A 12 volt battery, that varies between 9.6 and 14.4 volts, is converted to 24 volts that does not vary at all.

Step down converter: Power is taken from a voltage source, delivered to a load, and the output voltage is always less than the input voltage. If the input voltage drops below the output set point, the output will then drop with it.

Example: A 24 volt battery that varies between 19.4 and 28.8 volts is converted to 12 volts that does not vary at all.

Step up converter: Power is taken from a voltage source, delivered to a load, and the output voltage is always more than the input voltage. If the input voltage exceeds the output set point, the output will then increase with it.

Example: A 12 volt battery, that varies between 9.6 and 14.4 volts, is converted to 24 volts that does not vary at all.

Peak current: This term is usually applied to the load current. Since the electronic components can operate at much larger currents than the continuous rating, for a short time, the load can enjoy a surge for a short duration, usually two to. 12 seconds, All units have internal timers that automatically reduce the peak current to the continuous current after the first two to 12 seconds.

Recommended input voltage: This voltage is usually 80% of the maximum rating of the power transistors inside the unit. If the input voltage exceeds 1.25 times the recommended input voltage, damage will occur to the unit. Many models have automatic shut off that will protect the unit if the input voltage is excessive, but as the input voltage is increased, eventually the unit will violently fail.

Output ripple: This is an AC (alternating current) voltage that is riding on top of the DC (direct current) voltage at the output of the unit. It is sinusoidal and is generally expressed in max RMS. It is at the switching frequency of the unit, and will vary with variations of input and output voltage.

DC Bus: This is the DC (direct current) power supply that is connected to the input of the unit. It is expressed in volts, i.e., a 24 volt battery.

Courtesy of Zahn Electronics manufacturer of motor controls and DC/DC converters.

RELATED ARTICLE: Energy woes in the future?

"It's still touch-and-go as to whether there will be sufficient drilling for next winter--that's why there's so much uncertainty in the price of natural gas," said Jim Williams an analyst with a consulting group for the energy industry in June. "My hunch is we'll make it," he added, "but two, three or four years on--that's another question."

Another energy analyst worried that a hot summer may drain natural gas supplies.

Energy derived from natural gas accounts for 24 percent of total energy consumed in the United States, according to the Energy Information Administration. High energy costs hurt companies involved in manufacturing and heavy industry the most, as those sectors tend to guzzle large amounts of energy as they produce products like aluminum and chemicals. Natural gas is also used to produce fertilizer, so manufacturers of ag products are likely to pass on the higher production cost to farmers.

"You might find that farmers won't be buying that new tractor until next year because they need money to buy fertilizer," Williams said.

CHRIS LAFORGE

GREAT NORTHERN SOLAR

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