TeraOhm 5kV
21
[ ]
[ ]
[ ]
V
s
F
U
t
C
.
.
3
10
3
max
=
µ
,
where:
t ...........period of first time unit (e.g. 1min)
U .........test voltage.
DIELECTRIC DISCHARGE TESTING (DD)
DD is the diagnostic insulation test carried out after the completion of the Insulation
Resistance measurement. Typically the insulation material is left connected to the test
voltage for 10
÷
30 min and then discharged before DD test is carried out. After 1 minute
a discharge current is measured to detect charge re-absorption of the insulation
material. A high re-absorption current indicates contaminated insulation mostly based on
moisture:
[ ]
[ ] [ ]
F
C
V
U
mA
Idis
DD
.
min
1
=
,
where:
Idis 1min...... discharging current measured 1 min after regular discharge
U ................. test voltage
C ................. capacitance of tested object.
Measurement procedure:
-
Connect the test leads to the instrument and to the measured object.
-
Press the
START
key to start the measurement.
-
Wait until set timer runs out, result is displayed.
-
Wait until the object under test has discharged
-
The result (see the right part of the figure 11.) can optionally be saved by pressing
the
MEM
key twice, see the chapter 6.1. Store, Recall and Clear Operation.
Legend of displayed symbols:
DIAGNOSTIC TEST
Name of selected function
Off (Fil1, Fil2, Fil3)
Filter type enabled, see the chapter 5.3.
Configuration
1000V
Set test voltage – step 50 V
U=1056V
Actual test voltage – measured value
I=0.04nA
Actual test current – measured value
>1.00T
Ω
Ω
Ω
Ω
Insulation Resistance –
result
C=1.3nF
Capacitance of measured object
tr:00min 15s
Set timer value
bar
Analog presentation of Riso result
R01min=>1T
Ω
Resistance value measured after set time 1
R02min=>1T
Ω
Resistance value measured after set time 2
R03min=>1T
Ω
Resistance value measured after set time 3
PI1=0.99
PI as ratio of R02/R01
PI2=1.21
PI as ratio of R03/R02
DD=__
DD result
