As shown in the illustrated electronic overload relay, if the full load amp setting accurately represents the motor full load current of 6 amps and the trip class dip switch settings are for a trip class of 20, what statement is true assuming that the locked rotor current is 6 times the full load current. See illustration EL-0182.
• Trip class on an electronic overload relay (Class 5, 10, 20, 30) – what specific overload condition it refers to. • Relationship between full load amps (FLA) and locked rotor current (given here as 6 × FLA). • How the time in seconds in the trip class definition relates to the percentage (multiple) of FLA.
• Look at the illustration and note what the trip class dip switches actually label (5, 10, 20, 30). What motor current level are those times normally referenced to? • If the motor draws 6 × FLA at locked rotor and FLA is 6 A, what is the actual current in amps during this condition, and which answer choice uses that same current? • Which answer choices are talking about tripping at normal running current instead of at a high multiple of FLA? Should an overload relay of this type trip in that time at just FLA?
• Be sure you know that trip class time is specified at a particular multiple of FLA, not at any random current. • Confirm the locked-rotor current calculation: 6 × 6 A = ? and match that value to the options. • Eliminate any choice where the current level or the time does not match the definition of trip class 20 at locked-rotor current.
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