Overvoltage
category In brief Examples
CAT IV Three-phase at
utility connection,
any outdoor
conductors
•
Refers to the “origin of installation,” that
is, where low-voltage connection is made
to utility power
•
Electricity meters, primary overcurrent
protection equipment
•
Outside and service entrance, service
drop from pole to building, run between
meter and panel
•
Overhead line to detached building,
underground line to well pump
CAT III Three-phase
distribution,
including singlephase commercial
lighting
•
Equipment in fixed installations, such as
switchgear and polyphase motors
•
Bus and feeder in industrial plants
•
Feeders and short branch circuits,
distribution panel devices
•
Lighting systems in larger buildings
•
Appliance outlets with short connections
to service entrance
CAT II Single-phase
receptacle
connected loads
•
Appliance, portable tools, and other
household and similar loads
•
Outlet and long branch circuits
–
Outlets at more than 10 meters (30 feet)
from CAT III source
–
Outlets at more that 20 meters (60 feet)
from CAT IV source
CAT I Electronic
•
Protected electronic equipment
•
Equipment connected to (source) circuits
in which measures are taken to limit
transient overvoltages to an appropriately
low level
•
Any high-voltage, low-energy source
derived from a high-winding resistance
transformer, such as the high-voltage
section of a copier
Tab le 1. Over voltage installation categories. IEC 61010 applies to low-voltage
(< 1000 V) test eq uipment.
Built to withstand harsh
environments
with the highest
safety ratings
Rated all the way to CAT IV
ScopeMeter test tools are rugged solutions built for industrial troubleshooting.
The new Fluke 190 Series II are doubleinsulated floating oscilloscopes safety
rated for measurements in CATIII
1000V/CAT IV 600V environments.
Measure from mV to kV safely
Independent isolated inputs allow you
to make measurements in mixed circuits
having different ground references reducing the risk of accidental short circuits.
Conventional bench oscilloscopes without special differential probes and isolation
transformers can only reference measurements to line power earth ground.
With standard probes that cover a wide
application range from mV to kV, you’re
ready for anything from microelectronics to
heavy-duty higher voltage electrical applications.
IP-51 rated for harsh
environments
Rugged and shock-proof, ScopeMeter
portable oscilloscopes are built for dirty,
hazardous environments. With its sealed
case, it can endure
dust, drips, humidity
and airborne pollutants. Every time you
reach for ScopeMeter you can be confident
it will work reliably wherever your work
takes you.
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