Surge loads are loads that require an additional surge of current (inrush current) for a brief period upon starting, typically a few hundred milliseconds and at most a few seconds. This additional current is required to charge capacitors or to physically start a motor that is at rest. Once the capacitors are charged or the motor is spinning the amount of current to keep the capacitors charged or the motor spinning is much less. Common surge loads include refrigerators, compressors, fans, power tools and blenders. The current that a surge load requires could be as much five times as much the standard current draw for the load. On appliance or motor labels the surge requirement will be expressed as Locked Rotor Amps (LRA), although many surge loads do not include this information. If it is not possible to find information about the LRA for an appliance, then a common value of 3 times operating current may be used for design purposes.
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Surge loads are loads that require an additional surge of current (inrush current) for a brief period upon starting, typically a few hundred milliseconds and at most a few seconds. This additional current is required to charge capacitors or to physically start a motor that is at rest. Once the capacitors are charged or the motor is spinning the amount of current to keep the capacitors charged or the motor spinning is much less. Common surge loads include refrigerators, compressors, fans, power tools and blenders. The current that a surge load requires could be as much five times as much the standard current draw for the load. The labels on appliances and motor often do not have information about surge requirements, but if the label does have information it will be expressed as Locked Rotor Amps (LRA). If it is not possible to find information on the label or from the manufacturer, a value of 3 times operating current is commonly used for the load analysis.
Latest revision as of 16:05, 15 March 2021
Surge loads are loads that require an additional surge of current (inrush current) for a brief period upon starting, typically a few hundred milliseconds and at most a few seconds. This additional current is required to charge capacitors or to physically start a motor that is at rest. Once the capacitors are charged or the motor is spinning the amount of current to keep the capacitors charged or the motor spinning is much less. Common surge loads include refrigerators, compressors, fans, power tools and blenders. The current that a surge load requires could be as much five times as much the standard current draw for the load. The labels on appliances and motor often do not have information about surge requirements, but if the label does have information it will be expressed as Locked Rotor Amps (LRA). If it is not possible to find information on the label or from the manufacturer, a value of 3 times operating current is commonly used for the load analysis.
