BEKA BA354NE, Руководство пользователя

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Fig 16 Loop powered backlight
To strictly comply with the requirements of
EN60079:14
Electrical Installation in Hazardous
Areas , each of the wires entering the hazardous
area should be individually fused and contain a
means of isolation. However, in practice
instrumentation energised by a current limited power
supply that can be switched off is often considered
adequate.
10.4.2 Separately powering the backlight
The optional backlight may also be powered from a
separate safe area power supply as shown in
Fig 17.
Fig 17 Separately powered backlight
The separately powered backlight is a current sink
which will draw a constant 35mA when the supply
voltage is equal to or greater than 11V. At lower
supply voltages the backlight will continue to
function but with reduced brilliance.
The ATEX certificate therefore only specifies the
maximum safety input voltage Ui for terminals 12
and 14.
Ui = 30V
To strictly comply with the requirements of
EN60079:14
Electrical Installation in Hazardous
Areas , each of the wires entering the hazardous
area should be individually fused and contain a
means of isolation. However, in practice
instrumentation energised by a current limited power
supply that can be switched off is often considered
adequate.
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