Electric Motor Control Basics - Book - Page 61
Applying Motor Control in a Wastewater Application
• Class 10 is a quick trip rating, suitable for submersible pumps used in water and
wastewater industries. This rating indicates that the bimetallic overload relay
will trip automatically within 10 seconds of the overload condition.
• Class 20 is the standard and ideal for general motor applications.
• Class 30 is a slow trip rating, which is suited for motors that drive high inertia
loads and require long starting periods.
These features help minimize energy consumption and increase motor efficiency.
3. Motor Protection Circuit Breaker:
Designed for protecting motors from short circuits, phase-loss, and overloads, motor
protection circuit breakers (MPCB’s) are alternatives to thermal overload relays, and
are equipped with several advanced features.
Commonly used in many water pumping systems, these circuit protection
components are used as manual motor controllers or paired with contactors in
several multi-motor applications. Motor protection circuit breakers are mainly
distinguished as open or enclosed. The difference between these types is where
the circuit breaker is secured, either inside an enclosure or open in the panel. Most
advanced motor protection circuit breakers offer space savings, as they are designed
without individual motor branch circuit fuses, overload relays, or circuit breakers.
Part 1, Contactors
Basics: Part 2,
Basics: Part 3,
The Benefits of Type E/F
Basic Pump Control:
Three Phase DOL Starter
Control of an Electric Pump
Applying Motor Control
in a Wastewater
NEMA vs IEC Motor