Grounding Terminal Connection - Mandatory
Any person that gets in contact with
Helios
may carry an electrostatic charge of
several thousands of Volts. Drawing one’s finger near to the
Helios
metal panel may
result in spark discharge. The purpose of the grounding terminal is to protect the
product against this discharge. The terminal carries the charge from the panel to the
ground directly, not through the
Helios
circuits.
Where no grounding cable is available, it is possible to connect the grounding
terminal with any of the telephone line terminals*). In some telephone systems one line
terminal is directly connected with the ground, the others carry current to the ground
through overvoltage protection.
*) Note: This connection eliminates direct connection of the line conductor onto the
panel because there is a protective element between the panel and the grounding
terminal.
Separate Button Backlight and Electric Lock Feeding
Separate power supplies are necessary where the lock requires voltage higher than 12
V. In this case, an additional power supply (12V) must be used to illuminate the button
backlight - see the figure below. Other reasons for such connection are the effort to
minimise consumption from the back-up supply (which supplies the lock, not the
backlight), or just that two weaker power supplies are available
tel.
line
Supply
AC or DC
max.12V
Supply
AC or DC
max.48V
El. lock
26
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