Screen Service
SDT 200UB - 500UB ARK-1 ATSC
General information
July, 2009
v 1.0
Page 1 - 4
1.4 PROCEDURE FOR ESTABLISH THE ABSENCE OF VOLTAGE
Follow these simple steps for establish the absence of voltage:
¾
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 supp!y 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.
¾
Capacitors which are connected to a circuir isolated frcm its supply shall be discharged and have
their terminals permanently short-circuited and the casing earthed during the whole period of the
work.
¾
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.
¾
Before any maintenance work is carried out on automatic or remote controlled equipment, the
remote swithching circuits shall be made inoperative.
1.4.1 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.
