Application Note

2 Fluke Corporation Load studies: six common mistakes when conducting a load study
Fluke Corporation
PO Box 9090, Everett, WA 98206 U.S.A.
Fluke Europe B.V.
PO Box 1186, 5602 BD
Eindhoven, The Netherlands
For more information call:
In the U.S.A. [phone] or
Fax [phone]
In Europe/M-East/Africa [phone] or
Fax [phone]
In Canada (800)-36-FLUKE or
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From other countries [phone] or
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Web access: http://www.fluke.com
©2013 Fluke Corporation.
Specifications subject to change without notice.
Printed in U.S.A. 8/2013 6000863A_EN
Modification of this document is not permitted
without written permission from Fluke Corporation.
2. Not installing the logger
at the correct disconnect
or panel
Although it may sound obvi-
ous, the technician installing
the logger must verify that he is
installing the logger at the cor-
rect disconnect or panel. Many
locations have multiple discon-
nects and panels and it may not
be clear which one is the target
of the load study. When in doubt,
contact the person requesting the
study and verify the individual
load or panel to be monitored.
3. Not verifying that the
power source is live and that
it is not a switched outlet
Load studies are performed at a
wide variety of locations, such
as apartment buildings, com-
mercial office buildings, industrial
facilities and retail stores. With
older model loggers, standard
procedure is to plug the logger
in to a convenient outlet located
near the panel under study. The
technician installing the logger
must verify that the power source
is live and is not a switched
outlet controlled by a switch,
time clock, or photocell. If the
outlet is switched ON and OFF
on a regular basis the logger’s
batteries will be drained and the
logger will stop recording.
4. Not labeling the
power cord
The outlet that powers an energy
logger may not be located imme-
diately adjacent to the load being
monitored, requiring an extension
cord from the outlet to the logger.
(A logger that is capable of being
powered from the measurement
circuit is preferred). The exten-
sion cord must be installed so it
is not subject to physical hard-
ship, does not present a hazard
to personnel, and cannot be
unplugged inadvertently. Placing
a piece of adhesive tape on the
wall near the outlet with DO NOT
UNPLUG written on it or having
a specifically designed sign can
prevent the unplugging of the
extension cord by janitorial or
maintenance staff.
5. Incorrectly setting up
the logger
Always perform a simple check-
ing routine before starting the
logging session, to ensure all the
voltage phase connections match.
Confirm phase A from the logger
goes to phase A conductor and
B to B and C to C. Then verify
correct polarity for each current
probe. The arrow on the cur-
rent probe should point towards
the load. Check each phase to
make sure they all point in the
same direction. Finally, verify the
instrument is reading correctly:
Power is measuring positive
(if the load is operating) and
power factor shows a reason-
able looking value for the type
of load. Using an instrument that
automatically checks, highlights
and corrects connection errors is
a definite ‘nice to have’.
6. Not verifying that
recording has begun
Setting up an energy logger
to perform a load study is a
straightforward task, but the
simplest mistake—not turning on
the recording function—can still
be made. After confirming the
appropriate current and voltage
leads are connected to the load,
select your recording parameters
using the buttons and menus
on the unit and push the “Start
Logging” or “Record” button. You
should see both a message and
an icon on the logger’s screen
indicating logging has begun. It
is a good practice to wait through
the first recording interval and
verify the logger has recorded
its first value. Then you can be
absolutely certain recording has
begun and the setup is correct.