Amperage (Current):Definition: Quantity of electricity (coulombs) to pass through a given cross sectional area in a given unit of time. Quantity of water flowing from a hose would illustrate current.FLA: Full-Load Amps: Amount of amperage drawn when motor is working at rated horsepower.RLA: Running-Load-Amps: Same as FLA.LRA: Lock-Rotor-Amps: A motor draws a surge of amperage when it starts to get the rotor rotating and to achieve the rated horsepower. This amperage draw is approximately 6 x FLA of the rated motor for six to eight seconds.The sizing of the starter, wiring, circuit breaker and disconnect switch are based on FLA of the motor selected.Voltage:Work done in carrying a charge between two different points. The pressure at which water is exiting a hose would illustrate voltage.The higher the voltage, the lower the FLA of the motor. This equates to smaller sizes for wire, starter and disconnect.Watts:Amount of electrical power needed to do work – move air, pump water, compress refrigerates, heat spaces, etc.Usually measured in kilowatts – 1,000 watts.1 KW-hr equals 3,412 BTU1s.746 KW equals 1 Hp.Watts = volts x amperes. If voltage source is three phase multiple by square root of 3 – 1.732. 3 phase watts – volts x amps x 1.732.Phase:Electricity is generated and transmitted at three phase. This equates to three “hot wires” vectorally, 120 degrees apart. More power can be transmitted at the same voltage, because of the 1,732 multiplier.The voltages within buildings are usually derived from 480 volt and/or 208 volt three phase system.If 480 and 208 volt are divided by the square root of 3, the phase to neutral voltage will be obtained – 277 volt and 120 volt respectively. The neutral acts as the path to ground for the system voltage.Single phase 48 volt or 208 volt (usually only 208 volt, single phase) is obtained by tapping two of the three “hot phase conductors.”


You are watching: What does lra mean in electrical terms

Post navigation

← Plumbing and Electrical CoordinationElectrical Terminology for the Mechanical Designer Part 2 →

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Comment

Name *

Email *

Website


Commissioning Experience

Our in-house commissioning engineers work in collaboration—and in the trenches—with our mechanical and electrical engineers.

Learn More
Starting a Project?

We craft solutions that are creative, contemporary, reliable and sustainable.

Contact Us


See more: Neck Of The Woods Def In Your Neck Of The Woods Meaning Of This Popular Idiom?

*

LESSONS LEARNED

As part of aramuseum.org’s project management regimen, a series of “Lessons Learned” Round Tables have been established as…

Read More

*

aramuseum.org is Maryland’s mechanical, plumbing, and electrical (MEP) engineering firm located in Towson, Baltimore, MD.