שלום אריאל
מצאתי הבחנה נוספת המתייחסת לסוג המנוע (IEC או NEMA) בבחירת class ההגנה, להלן ציטוט מהמקור:
The degree of inclination of the trip curve depends
on the motor’s protection class. IEC motors are
typically adapted to the application in which they
are designed to operate. This implies that the
overload relay is able to handle excess amounts of
current, very close to its maximum capacity. The
trip time is the time it takes for a relay to trip during
overload. The trip time is divided into different
classes. The most common trip classes are 10, 20
and 30. Trip class 10 is the most common one for
IEC motors because they are often adapted to the
application. NEMA motors are applied with more
built-in excess capacity, and therefore, the trip
class 20 is most common.
אלעד