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Siemens Building Technologies Basic Documentation RVD230 CE1P2383en
HVAC Products 33 Engineering 27.05.2004
33.2 Relays
The maximum permissible electrical rating of the relays used in plant types x–4 for
switching the d.h.w. actuators is 24 VA. Higher loads will shorten the contacts’ life.
33.3 PWM output
The PWM output is designed for safety extra low-voltage. The distance between the
connected cable (device) and active components (e.g. AC 230 V) must be in compli-
ance with the requirements for safety extra low-voltage.
33.4 Lightning protection in M-bus plants
Lightning can adversely affect the proper functioning of M-bus plants. For this reason,
the following rules must be observed:
• If bus cables are laid outside buildings, the devices are exposed to transients of light-
ning strokes and must be appropriately protected
• Every bus cable and the devices to be protected demand matching protective equip-
ment
• The protective function is ensured only if the installation is in proper working order
For notes on installation in compliance with EMC requirements, refer to Data Sheet
N2034.
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