Motors are NOT generators of electricity. They consume electricity. So what sense do these statements make which confuse me to no end as I read about Short Circuit Calculations?????? Can any of you help me to understand this.
"Motor short-circuit contribution, if significant, should be added at all fault locations throughout the system. A practical estimate of motor short-circuit contribution is to multiply the total motor full-load current in amperes by 4. Values of 4 to 6 are commonly accepted"
"Motor Contribution Limitation: The first critical requirement limits the application of a series combination rating where motors are connected between the line-side (protecting) device and the load-side (protected) circuit breaker. NEC® 240.86(B) requires that series ratings shall not be used where the sum of motor full load currents exceeds 1% of the interrupting rating of the load-side (protected) circuit breaker."
" Motor Contribution If motors are connected between the series rated devices, is the combined full load current from these motors less than 1% of the downstream circuit breakers’ interrupting rating (individual or stand alone interrupting rating) per 240.86(B)? "