Electric Motor Control Basics - Book - Page 87
Understanding IP Ratings
Why is Protection Against Exposure Important?
Any time someone comes into contact with energized electrical equipment, there is an
inherent danger. One of the most common risks associated with this environment is an
arc flash.
Also called a flashover, this phenomenon occurs when low impedance connections form
within an electrical system. This moves an electrical discharge through the air, which
can travel between voltage phases or to the ground.
When this happens, it causes the air pressure and temperature between the electrical
conductors to rise, leading to an arc blast. Temperatures soar to up to 35,000 degrees
Fahrenheit in less than one-thousandth of a second and a sound wave (160-decibel or
higher) forms.
During the blast, molten metal and shrapnel hurl out at speeds of up to 700 miles per
hour. The event lasts mere milliseconds but can lead to death, severe burns, or hearing
loss. In fact, up to 80% of all electrical burns are arc blast-related, most of which require
a hospital stay of two to four months.
In addition to worker injuries, arc blasts also damage or ruin equipment and halt
production.
Industrial Control
Basics:
Part 1, Contactors
Industrial Control
Basics: Part 2,
Overload Relays
Industrial Control
Basics: Part 3,
Starters
The Benefits of Type E/F
Motor Protection
Circuit Breakers
Basic Pump Control:
Three Phase DOL Starter
Control of an Electric Pump
Applying Motor Control
in a Wastewater
Application
NEMA vs IEC Motor
Controls
Understanding
IP Ratings
87
