Megger SR-98, Инструкция по эксплуатации

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3. Using the cursor key, cursor down to
Out Freq:
. Depending on the model
number of the SR-98, the defaulted frequency may be either
60 Hz
or
50 Hz
. To
change the output frequency, rotate the control knob until the desired harmonic is
displayed. For example, the second harmonic of 60 is 120 Hz.
4. Press
PREV SCREEN
.
5.
With both units
MODE SELECT
set to
MAINT.
(MAINTAIN), press the ARM M/S
button on both units. Press the Master Unit
INIT
button.
6.
Rotate the Slave Unit Control Knob and increase current until the desired
harmonic current is set. For example, set to 1 Ampere.
7. Rotate the Master Unit Control Knob and increase the fundamental current until
the
TRIP
LED turns
ON
(and the horn sounds, if the horn is set on).
8.
Read and record the two currents. Turn off the
AC CURRENT MAIN
outputs off
by pressing the Master Unit
SOURCE RESET
button (turns all outputs off,
including the DC AUX voltage). To repeat the test, simply press the DC AUX
button ARM M/S buttons and the Master INIT button. The outputs will turn on at
the same values where you turned them off.
9.
To calculate the percent of harmonic restraint use one of the equations below:
%
Harmonic Restraint = __2 nd Harmonic_Current__ * 100
√
(
Fundamental)
2
+ (2nd Harmonic)
2
For example, a General Electric type BDD, harmonic restraint relay, set for a 20
% harmonic restraint, might have typical values of 1 Ampere 2 nd Harmonic
Current (Slave Unit) and 4.9 Amperes Operating Current (Master Unit). The
calculation would look like the following,
%
Harmonic Restraint = __ 1 * 100
⇒
20 %
√
(
4.9)
2
+ (1)
2