Application Note

Making the measurements
Measurements for this procedure
will be made on a 480 V three
phase drive control at the control
panel terminal strips using the
new Fluke 289 digital multimeter.
These procedures would also be
valid for lower voltage 3 phase
drives powered by either single
or 3 phase supply voltages. For
these tests the motor is running
at 30 Hz.
Input Voltage
To measure the ac voltage supply
to the input side of the drive at
the drive:
1. Select the 289’s ac voltage
function.
2. Connect the black probe to
one of the three phase input
terminals. This will be the
reference phase.
3. Connect the red probe to one
of the other two phase input
terminals and record the
reading or save it to the
289’s internal memory.
4. Leaving the black probe on
the reference phase now
move the red probe to the
third phase input and record
or save this reading to the
289’s internal memory.
5. Check to make sure that
there is no more than a 2 %
difference between these
two readings.
3 Fluke Corporation Multimeter measurements on variable frequency drives using the new Fluke 289 DMM
1. Connect the clamp to the 289’s common and
400 mA input jacks.
2. Select the mA/A ac function.
3. Place the clamp around each of the input supply
phase cables in succession, recording or saving
to internal memory each of the readings as they
are taken. Since these clamps output 1 milliamp
per amp, the milliamp readings shown on the
289 display are the actual phase current read-
ing in amps.
Hall Effect type (AC/DC) clamp (i410, i-1010)
1. Connect the clamp to the 289’s common and
V/Ω input jacks.
2. Select the 289’s mVac voltage function for cur-
rent measurements up to 500 amps.
3. Since the lowest range on the 289 is
50.000 mVac push the range button once to
place the meter in the 500.00 mVac range if
the drive current will exceed 50 amps for the
measurement.
4. Place the clamp around each of the input supply
phase cables in succession, recording each of
the readings as they are taken or again save to
the 289’s internal memory. Since these clamps
output 1 millivolt per amp, the millivolt readings
shown on the 289 display are the actual phase
current reading in amps.
289 with i1010
AC/DC Clamp accessory
The new Fluke 289 also contains
internal memory for saving
specific individual measurements
that can be recalled on screen or
downloaded to reports generated
by Fluke View Forms
®
software.
Input Current
Measuring the input current
requires using a current clamp
accessory. This is because it is
not practical to “break the circuit”
to make an in-line series current
measurement. Regardless of the
type of clamp used, check to
insure that all readings are
within 5 % of each other for
proper balance.
Transformer type clamp
(Fluke models i200, i400,
80i-400, 80i-600A, i800)