Siemens RVD240 - Relays; PWM Output; Lightning Protection in M-Bus Plants

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Siemens Building Technologies Basic documentation RVD240 CE1P2384en
HVAC Products 32 Engineering 27.05.2004
32.2 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. Greater loads will shorten the contacts’ life.
32.3 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.
32.4 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
lightning strokes and must be appropriately protected
• Every bus cable and the devices to be protected demand matching protective
equipment
• 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.