Front Panel Operation - 4
49
On three-phase ac sources, phase 1 is normally offset by 0
°
from the internal phase reference while
phase 2 and phase 3 are offset by 240
°
and 120
°
respectively. Therefore, synchronized transient events
will occur at the phase angle programmed for the phase 1 output, but at different phase angles on the
phase 2 and phase 3 outputs.
This is illustrated in the following figure, where the transient occurs at the 90
°
angle programmed for the
phase 1 output, but at 330
°
and 210
°
for the phase 2 and 3 outputs, because of the default offsets for
these outputs.
4
02
Trigger
VOLT T level
VOLT level
VOLT T level
VOLT level
VOLT T level
VOLT level
03
01
90
0
210
0
330
0
phase = 0
phase = 120
phase = 240
Figure 4-8. Phase Synchronization on Three-phase Sources
Example
Display
m
This example synchronizes a change at 90
°
on phase 1. First, access the
Voltage menu and program the immediate and triggered voltage levels,
followed by the voltage transient mode. Check that the
φ
1,
φ
2, and
φ
3
annunciators are all lit, indicating that commands will be sent to all three
phases. If not, press
Phase Select
until all three annunciators are lit.
Press
Trigger Control
. Press
ô
until you access the sync source command.
On the Entry keypad, press
°
once to obtain PHASE. Press
Enter
.
Access the Trigger Control menu again and press
ô
to access the sync phase
reference parameter. On the Entry keypad, program a 90
°
phase reference by
entering
9 0 Enter
.
Then press
Trigger Control
and
Enter
, followed by
Shift Trigger
.
VOLT 120
VOLT:T 150
VOLT:M STEP
SYNC:SOUR PHASE
SYNC:PHAS 90
INIT:IMMED