17
RMO40TD Getting Started
Repeat this procedure as often as needed until the results for RIPPLE and RESISTANCE are obtained
for all Tap Changer positions.
Test is completed by pushing
STOP
.
When measurement is completed (after pressing
STOP
) RMO40TD switches to the
TapC
menu
and starts current discharging. During the current discharging process, the discharging LED lights
and alarms beep.
Discharge is completed when LED discharge and the buzzer are OFF. Also, during that period
“Discharging” message is shown on the display. During discharging process it is not possible to
start another measurement.
A properly working tap changer differs from malfunctioning one in a current discontinuity during the tap
change, by the magnitude of the current ripple value. A discontinuity will result in much higher current
ripple value (99 % or 100 %) than a properly functioning tap changer.
Note
:
Current ripple value depends on the construction of the tap changer. It is recommended to
compare current ripple values between each other got on one transformer. Also, it is recommended to
compare current ripple results on one transformer with results from some previous test in order to follow
conditions of that tap changer.
Figure 6-17 shows indication about possible tap changer bad conditions during the change from tap to
tap.
If current circuit is opened during the change from tap to tap, message „Discontinuity“ will be shown on
the display, red LED will light and buzzer will beep continuously. Discharging process starts.
Discharge Current
The voltage at the RMO40TD output generation is immediately stopped, but current still flows, because
of the inductivity of test objects.
Figure 6-16:
The
TapC
menu during
discharging
Figure 6-17:
The
TapC
menu
showing much higher
current ripple value
Figure 6-18:
Message
"Discontinuity"
