Start Characteristics
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This page contains test results and measurements for various electrical loads. Note that these measurements are representative only for the specific models shown and under the particular test conditions. Different conditions can alter both the current values and starting times. Slightly different line voltages will affect results as will the wire size and length feeding the load. Ambient temperatures and thermostat settings will affect refrigeration compressor current demands. For well pumps, the pressure settings and the depth that the pump is positioned will affect measured results. Additional test measurements are being added to this page on a regular basis. If you have some tests results that would be helpful to others, send them to us for posting here.
Refrigerator Starting Current This test measured the starting current for a refrigerator with the following nameplate data.
Results of one measurement are shown in the plot below. It shows a maximum inrush current of about 13 amps which lasts only about one-half second. Also, the running current is significantly less than the nameplate value. It should be noted that most refrigerators (including this one) are "frost free." This means that on a regular basis a timer shuts off the compressor and turns on resistance heaters to clear frost buildup in the freezer section. This defrost current was not measured and is probably greater than the compressor running current. This may explain the large difference between the nameplate current value and the measured value.
Freezer Starting Current This test measured the starting current for a freezer with the following nameplate data.
Results of one measurement are shown in the plot below. It shows a maximum inrush current of less than 5 amps which lasts only about 0.3 seconds. Also, the running current is significantly less than the nameplate value. It should be noted that most freezers are "frost free." However, this one is not.
Well Pump Starting Current This test measured the starting current for a well pump motor. The motor is rated 3/4 hp and 240V. Results of one measurement are shown in the plot below. It shows a maximum inrush current of about 18 amps which lasts only about 0.2 seconds.
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