27
detail concerning the calculation performed:
The insulation resistance varies with the measurement temperature. This dependence can be approximated by an exponential
function:
Rc = K
t
* R
t
where Rc:
insulation resistance referred to 40°C.
R
t
:
insulation resistance measured at ambient temperature T.
K
t
:
coefficient defined as follows:
K
t
= (1/2) ^ ((40 - T)/
∆
T)
where
∆
T:
temperature difference at which the insulation resistance is halved.
4.2. ALArM kEy
ALARM
Press the ALARM key to activate the alarm defined using the CONFIG key (see 4.3) or in SET-UP (see §5). The
ALARM symbol is then displayed.
If the measurement is less than the alarm threshold, the instrument so indicates by the blinking of the ALARM
symbol on the display unit and the emission of an audible signal.
Press the ALARM key again to deactivate the alarm; the ALARM symbol disappears from the display unit.
4.3. CoNfIG kEy
4.3.1. bEforE tHE MEASUrEMENt
If the U-FIXED or U-VAR. test voltages have been chosen, there are two configuration screens. There is only one for the U-RAMP
and U-STEP test voltages.
Press the CONFIG key:
CONFIG
Total Run Time
---
Manual Stop
Manual Stop + DD
Timed Run (m:s)
2:00
Timed Run + DD
DAR (s/s)
30/60
PI (m/m) 1.0/10
CONFIG
CONFIG
Manual Stop: manual stoppage of the measurement.
Manual Stop + DD: manual stoppage of the measurement and calculation of the DD.
Timed Run (m:s): automatic stoppage of the measurement at the end of the programmed duration.
Timed Run + DD: automatic stoppage of the measurement at the end of the programmed duration and calculation of the DD.
DAR: automatic stoppage of the measurement at the end of one minute (or of the programmed time, if different).
PI: automatic stoppage of the measurement at the end of 10 minutes (or of the programmed time, if different).
It is always possible to stop a measurement during a test with programmed duration, by pressing the START/STOP button.
The
keys are used to select the
measurement configuration. The chosen
configuration is validated by pressing the
CONFIG key again.