Application Note

2 Fluke Corporation Power Quality Troubleshooting
While we’ve enjoyed enormous
benefits from the evolution of
solid state technology, the fact
is that the microelectronics at
the heart of that technology
requires clean power. Faster
speeds and lower voltages
mean that there is less and less
tolerance for anything less than
quality power.
Power Quality (PQ) covers a
wide range of issues, from volt-
age disturbances like sags,
swells, outages and transients,
to current harmonics, to perfor-
mance wiring and grounding.
The symptoms of poor PQ in-
clude intermittent lock-ups and
resets, corrupted data, prema-
ture equipment failure, over-
heating of components for no
apparent cause, etc. The ulti-
mate cost is in downtime,
decreased productivity and
frustrated personnel.
This application note gives
you information on how to
troubleshoot PQ problems. It
also gives you information on
how to start fixing those
Introduction
problems. But before grabbing
that meter, please read the
following cautionary notes:
1. Suggested measurements
should only be made by
qualified personnel who have
been trained to make these
measurements in a safe
manner, using proper
procedures and test tools
rated for work on electrical
power circuits.
2. To the best of our knowledge,
recommended solutions are
consistent with the National
Electric Code (NEC), but in
any case, NEC requirements
must not be violated.
3. We have tried to make the
information accurate and
current, but it is not intended
to be a substitute for the
specialized knowledge and
experience of professional
power quality practitioners.
What this application note offers
is a “starter kit,” not the final
word on PQ troubleshooting.
IEC 61010 establishes interna-
tional safety requirements for
low voltage (1000V or less)
electrical equipment for mea-
surement, control and labora-
tory use. The low voltage power
distribution system is divided
into four categories, based on
the proximity to the power
source. Within each category
are voltage listings—1000V,
600V, 300V, etc.
The key concept to under-
stand is that you should use a
meter rated to the highest cat-
egory, as well as the highest
voltage, that you might be
working in. For PQ trouble-
shooters, that means a meter
rated to CAT III-600V or CAT III-
1000V (the specifications for
CAT IV have not yet been de-
fined by IEC). We recommend
that you do not use CAT II rated
meters, scopes or test leads and
probes on CAT III circuits. The
CAT ratings should be marked
near the voltage inputs of the
instrument. Meters designed to
IEC 348, the previous standard,
will typically not meet the more
stringent safety specs of IEC
61010 CAT III-600/1000V.
IEC 61010 requires increased
protection against the hazards
of transient overvoltages. Tran-
sients can cause an arc-over
inside an inadequately pro-
tected meter. When that arc-
over occurs in a high energy
environment, such as a three-
phase feeder circuit, the result
can be a dangerous arc blast.
The potential exists for serious
harm to personnel as well as
damage to the meter. For more
information, see the Fluke appli-
cation note “ABCs of Multimeter
Safety” (document number
B0317UEN) and the Fluke video
“The ABCs of Digital Multimeter
Safety” (P/N 609104).
Independent Testing and
Certification
Manufacturers can self-certify
that they meet IEC 61010 specs,
but there are obvious pitfalls for
the end-user in self-certification.
Certification by an independent
testing lab provides assurance
that the meter meets IEC re-
quirements. Look for a symbol
and listing number of an inde-
pendent testing lab such as UL,
CSA, TÜV, VDE, etc. UL 3111, for
example, is based on IEC 61010.
Overvoltage
Category
Summary Description
CAT IV* Three-phase at utility connection, any
outdoors conductors (under 1000V)
CAT III Three-phase distribution (under 1000V),
including single-phase commercial lighting
and distribution panels
CAT II Single-phase receptacle connected loads
CAT I Electronic
*CAT IV product specifications are not yet defined in the standard.
International Safety
Standards for Test Tools
Table of Contents Page
Safety ............................................................2
Getting Started...............................................3
First Steps .....................................................3
Part I: Facility Distribution System
Section 1: Receptacle Branch Circuit ................... 4
Section 2: Service Panels ...................................... 8
Section 3: Transformers....................................... 10
Section 4: Electrical Noise and Transients........ 16
Section 5: Lightning Protection .......................... 21
Part II: Three-Phase Loads
Section 6: Polyphase Induction Motors ............. 22
Section 7: AC Adjustable Speed Drives ............. 25
Section 8: Commercial Lighting.......................... 30
A Lineup of Power Quality Culprits ............... 31
Test Tools....................................... Back cover