T-305E User Manual Version 3.5 | 19
vii.
Turn the
ADJUST
knob slowly until the voltage rises to the chosen value, press the
PULSE
button to ascertain whether the voltage is sufficient to break-down the fault. If the fault
does not break-down, raise the voltage further and repeat the process until break-down
occurs.
viii.
When the break-down voltage has been found, press the
PULSE
button again and check
the waveform on the T-906, which should allow the fault position to be identified.
ix.
Once the process is completed, discharge the cable and surge generator manually using
the discharge rod (see section 5.1 Using the discharge rod).
6.4
Secondary/Multiple Impulse Method (SIM/MIM)
The T-906 should be connected to the internal SIM filter of the T-305E through the
TRIGGER/SIGNAL port using the Lemo cable supplied.
Operational procedure:
i.
Turn the
MODE
knob to the
PULSE
position.
ii.
Turn the
TEST METHOD
to
SIM
.
iii.
Select a suitable capacitor bank setting.
iv.
Power on the T-305E, the green
STOP
button lights up.
v.
Turn the voltage
ADJUST
knob to the zero position, which enables the
START
button.
vi.
Press the
START
button, which then lights-up and the green
STOP
light turns off. Inside
the instrument, the noise of the HV protective device can be heard
vii.
Turn the
ADJUST
knob slowly until the voltage rises to the chosen value, press the
PULSE
button to ascertain whether the voltage is sufficient to break-down the fault. If the fault
does not break-down, raising the voltage further and repeat the process until break-
down occurs.
viii.
When the break-down voltage has been found, press the
PULSE
button again and check
the waveform on the T-906, which should allow the fault position to be identified.
ix.
Once the process is completed, discharge the cable and surge generator manually using
the discharge rod (see section 5.1 Using the discharge rod)
7.
DC Voltage Withstand Test
For power cables rated at 6kV or below, after the fault has been repaired, the T-305E can be
used to perform a DC voltage withstand test.
7.1
Cable Connection
Before commencing the test, disconnect the faulty cable and ground the metal sheath.
Note: This is the Working Ground, the zero-volt reference point during the discharging
process.
7.2
Performing the Test
Because the remaining charge on the cable may be significant, it should be thoroughly
discharged before the test. As a guide, it usually needs 5 minutes for the discharge process
(see section 5.1 Using the discharge rod).
