The Safety Trigger Switch - Elcometer 280 Guia Del Usuario

10 MANUALLY CALCULATING THE TEST VOLTAGE (continued)
For example:
Metric:
Imperial:
Experiment
Touch the probe on an unimportant area of the work piece. Increase
the voltage slowly and steadily until a spark passes through the
coating. Make a note of this voltage - it is the upper voltage limit.
Note: The dielectric strength can be calculated by dividing this voltage by the
coating thickness.
Tables and formulae
Alternatively, the correct voltage levels can be determined from
established Codes of Practice, e.g. NACE and ASTM.

11 THE SAFETY TRIGGER SWITCH

In order to minimise the possibility of accidentally switching the voltage
on, the Elcometer 280 is fitted with both a safety trigger switch (a) and
a voltage activation key (b).
The voltage will only be activated when:
1 The gauge is switched ON.
2 The safety trigger switch (a) is held, and
3 The voltage activation key (b) is pressed.
4 The signal return lead is fitted.
If the safety trigger switch is released when the
gauge is in operation, the voltage is
immediately disconnected.
If the safety trigger switch is held again within 3
seconds, the voltage will automatically re-
activate (without the need to press the voltage
activation key).
11
R
if you have 500 microns of coating (0.5mm) with a
dielectric strength of 6kV/mm, the upper voltage
will be 3kV.
if you have 20 mils of coating (0.02inch) with a
dielectric strength of 150kV/inch, the upper voltage
would be 3kV.
a
b
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