Compressor lra calculation

How much LRA in one ton compressor. How many LRA in one ton compressor. APPROXIMATELY inches in Hg. The LRA indicates how much amperage the motor will pull while trying to make the rotor spin inside the stator, if the rotor is locked up! What could caused it to lock up?

On reciprocating compressors , usually the crankshaft or a piston has broken.

So, what should you do when you have a compressor pulling LRA ? Many of the terms used to indicate a gas capacity are either vague or often misunderstood. In addition many applications require the compressor to operate under a variety of conditions resulting in a very wide range of capacities. Always refer to compressor performance or rating data for that compressor from the compressor manufacturer.

The best way to determine the correct amperage draw for a particular compressor is by referring to the rating chart for that compressor. Compressor manufacturers. In the case of a compressor , it is the motor that drives the compressor which can either be open drive with a pulley and belt assembly or enclosed within the compressor , which is known as hermetic (or semi hermetic).

Most hermetic compressors only have the LRA (locked rotor amps) on the compressor data plate.

The locked rotor amps tell you what the compressor will draw if the rotor cannot turn when the compressor is energized. But the operating current is not a fixed quantity. W for each ton (10BTU) of refrigeration effect. LRA which I believe means Locked Rotor Amps is the very high current draw when any electric motor has stalled in overloa or is just beginning to rotate when turned on. Form a clear, concise statement describing the purpose of the compressor.

Many compressors operate at more than one condition. Determine why and how often the various conditions occur. Examples: This compressor is to transfer liquid propane from railcars into a bulk storage tank. On low temp refrigeration equipment the compressor can over amp, if the evaporator is warm or hot.

Higher pressures from a warm evaporator exceed the design capacity. The compressor motor must work harder. An air conditioner that is not working on a hot summer day is very annoying and even potentially dangerous. If you are able to determine that the compressor can be repaired by replacing the capacitor, it is a simple process to fix it.

However, you need to make sure that you have the correct capacitor size. In our example, the nameplate indicates that the motor- compressor LRA is amperes. Adding this to the motor- compressor LRA of amperes gives us an equivalent LRA for the combined load of 103. The LRA (locked rotor amperes, short circuit current, locked rotor current) is dependent on the design type of the motor and is not to be considered in sizing the feeder under normal circumstances.

If it woul the feeders would be way oversized.