Using electricity for refrigeration compressors requires information.
You have to know the correct voltage and amperage.
The voltage is simple. Either you have it or you don't.
What about amperage?
The amperage varies. The more load placed on the compressor motor, the more amperage it draws.
But how high can the amps go before you start overloading the compressor?
Enter RLA (run load amps)!
If you check the data plate, chances are you'll find a number stamped into the RLA box.
That number represents the maximum amps allowed.
If you exceed that figure by a substantial amount, the motor will overheat and damage may result.
What is a substantial amount?
I use 15%.
Example: A RLA of 20 amps should not exceed 23 amps. 15% of 20 is 3 amps, added to 20 equals 23 amps.
In most cases, I've found that properly sized and operating refrigeration equipment rarely reaches this maximum.
What are the exceptions?
On low temp refrigeration equipment the compressor can over amp, if the evaporator is warm or hot.
The compressor is sized to pump the lower pressures you'll find on lower temperature evaporators.
Higher pressures from a warm evaporator exceed the design capacity. The compressor motor must work harder. The RLA is exceeded.
How is this problem solved?
If may become necessary to install a CPR valve.
So, don't sweat the RLA amount! It's there to give you an indication of the load being placed on the compressor.
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