LEM MachineTest 204 Manuel D'utilisation page 17

MEASUREMENTS
In linear mode the Residual Voltage Tester recognizes three standard mains
voltages automatically:
In order test result to be always on "safe side", measured residual voltage is
scaled to maximal possible value i.e.:
If input voltage is out of any standard voltage ± 10%, then the tester scales
result to maximal actual value.
Example: Uin = 173 V (under standard voltage 230 V ± 10%) ⇒ result will be
scaled to 244 Vp = 173 V × 1.41
b) Non-linear mode
This mode shall be used when dealing with non-linear or unknown objects
which consist of R, L, C components and also non-linear internal components
(relays, gas lamps etc.). In this case a diagram of voltage decreasing (after
switching off tested object) may be quite unpredictable, see the figure below,
and can not be scaled to maximal voltage value.
Fig. 14. Diagram of voltage decreasing in case of non-linear components
are involved
Disadvantage of this mode is that the measurement must be repeated several
times in order at least once tested object to be switched off at nearly max. value
of mains voltage.
In order to assure reliable result (switching off at least once at approx. max. mains
voltage) the test should be repeated at least 15 times (mathematical statistics). Final
result is positive if all partial results were positive and is negative if only one partial
result was negative.
110 V.......................Uin = 110 V ± 10%
230 V.......................Uin = 230 V ± 10%
400 V.......................Uin = 400 V ± 10%
171 Vp = 110 V × 1.1 × 1.41 .......standard mains voltage 110 V
357 Vp = 230 V × 1.1 × 1.41 .......standard mains voltage 230 V
620 Vp = 400 V × 1.1 × 1.41 .......standard mains voltage 400 V
u
relay may be
switched off
16
t