General knowledge of motor protection
1 Why motor is easier to burn than before now?
Due to the continuous development of insulation technology,
motor designs require both increased output and size reduction, heat
capacity of new type electric motor getting smaller and smaller, less
load capacity;
Due to the increase of automated production, requiring
Motors generally run the frequent starting and braking, a variety of
ways such as rotating and variable load, make higher demands on
motor protection devices.
In addition, the electrical application of
much broader, often working in environments where extremely bad,
such as humidity, high temperatures, dust, corrosion, and other
occasions. All of these, resulting in a current motor is more easily
damaged than in the past, especially overload, short circuit, phase,
such as sweep the hearth failure occur most frequently.
2
Why conventional protection device protection effect is not good
enough?
Traditional motor protection thermal relay as the principal, but
thermal relays with low sensitivity, errors, poor stability, protection is
not reliable.
Facts too, even though many devices installed thermal
relay, motor damage and affect the normal production is still
widespread.