TEM A07EXXXX – 1 Unit Transmitters Page 10
3.5 Procedure for establish the absence of voltage
Follow these simple steps for establish the absence of voltage:
Before starting work on the equipment, it shall be isolated from the mains supply.
This disconnection shall always be checked by visual inspection.
Further precautions shall be taken to ensure that the mains supply cannot be restored whilst work is being carried
out.
After the mains supply has been disconnected, all other lines such as control, interlocking and modulation lines
shall be disconnected if they carry dangerous voltages.
Moreover, the antenna or the antenna transmission line shall be disconnected from the antenna terminal device
to prevent the introduction of dangerous voltages due to antenna pick-up.
When disconnection of the antenna or antenna transmission line is not possible, other suitable precautions shall
be taken, for example, earthing, when necessary at several places, to esablish absence of voltage.
These earthing connections shall be very short compared with the wave-lenght.
Capacitors which are connected to a circuir isolated from its supply shall be discharged and have their
terminals permanently short-circuited and the casing earthed during the whole period of the work.
The electrical charge retained by electrical machinery when stopped may, in certain cases, be sufficient to
cause a severe shock.
This shall be taken into account when making connections to an apparently "dead" machine.
Therefore all machinery shall be discharged and earthed using an adequately insulated lead for this purpose.
The discharge operation shall be repeated several times.
Before any maintenance work is carried out on automatic or remote controlled equipment, the remote
swithching circuits shall be made inoperative.
3.5.1 Procedure for determination of the absence of voltage
After the equipment has been isolated according to the standard EN60215, the absence of voltage shall be
determined at the work place.
This may be done by the use of voltage indicators, measuring instruments, glow discharge lamps for indicating
radio-frequency voltage or other suitable means.
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