Electric Motor Control Basics - Book - Page 77
NEMA vs IEC Motor Controls
IEC Features and Benefits
Most IEC contactor sizes allow you to match the contactor to the application
conveniently. This contrasts NEMA, where the sizes are standard across the industry.
With IEC, the contactor size ratings vary by manufacturer.
Normally, an IEC starter is almost half the size of a similar NEMA starter. However,
above 100A, the physical differences are negligible.
IEC products are more flexible and modular in nature and can snap on DIN rails
up to 75mm. This removes the need to drill holes for mounting each component
individually. Putting them into a panel becomes relatively easy.
IEC starters are sold as components comprising a contactor, an auxiliary block and
overload relay block. This way, you can assemble the parts yourself. You do this by
selecting the accessories you need and snapping them together without the use of
IEC-style thermal overload relays come with fixed thermal elements. Their
adjustment range may call for the complete overload when there are changes in the
NEC sec. 430-53 deals with contactors that need to be applied in group applications.
However, this isn’t unique to IEC only since other starters can be installed this way.
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