Calibrating Instruments
Calibrating RCD Test Functions 4
4-27
Touch (contact) Voltage
Touch voltage is the voltage difference between N and PE potentials. UUTs can usually
measure this voltage and display it as a measured value or detect crossing over the safe
voltage level (25 to 50 volts typical) with an indication of this event. Touch voltage
generated by the Calibrator depends on selected series resistance and setup nominal trip
current. It is scanned and displayed in this field.
To change nominal trip current:
1. Press the Trip I softkey.
2. Using the keypad, type in the desired nominal trip current value and press E or
use the softkeys to select the appropriate units.
Note
The Calibrator’s nominal trip current can be set between 3 and 3000 mA.
3. Press Exit to return to the RCD calibration main screen.
Although the Calibrator selects the most appropriate series resistance for RCD
calibration, you can manually select one of sixteen resistance values to adjust RCD
calibration performance. To change the series resistance:
1. Press the Setup softkey.
2. Using the cursor keys or rotary knob, highlight RCD and either press the Select
softkey or press in on the rotary knob.
3. Using the cursor keys or rotary knob, highlight Series resistance and either press
the Select softkey or press in on the rotary knob.
The series resistance is inserted into the test circuit to generate a non-zero touch
voltage. One of 16 fixed resistors between 25 mΩ and 1.8 kΩ (labeled R01 to R16)
are used for the series resistance setting. The resulting touch voltage can be
approximated by multiplying trip current times the series resistance value.
Note
Do not exceed maximum allowed current for the selected resistance.
Maximum current is displayed in brackets next to the series resistance in
the PARAMETERS area of the display.
4. Using the cursor keys or rotary knob, highlight the desired resistance and either press
the Select softkey, or press in on the rotary knob. Table 4-4 on page 4-24 lists the
available series resistance selections.
5. Press the Exit softkey to return to the RCD calibration main screen.
To change the current multiplier:
1. Press the I Mult. softkey.
2. Press the I Mult. softkey for the desired current multiplier value and either press the
Select softkey or press in on the rotary knob. Available multipliers are 0.5, 1, 1.4, 2,
and 5.
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