Basic Documentation

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Siemens VAV Compact Controller Modbus RTU A6V10631862_en--_e
Smart Infrastructure 2021-10-26
Regarding AC 24 V operating voltage, the following regulations must be complied with:
Regulation
Operating voltage
AC 24 V
The operating voltage must comply with the requirements for SELV or PELV:
• Permissible deviation of AC 24 V nominal voltage at the actuators: +/–20 %
Specification on AC
24 V transformers
• Safety isolating transformers as per EN 61558, with double insulation,
designed for 100 % on time to power SELV or PELV circuits
• Determine the transformer’s output by adding up the power consumption in
VA of all actuators used
• For efficiency reasons, the power drawn from the transformer should
amount to at least 50 % of the nominal load
• The transformer’s nominal capacity must be at least 25 VA. With smaller
transformers, the ratio of no-load voltage and full load voltage becomes
unfavorable (> + 20 %)
Fusing of
AC 24 V operating
voltage
Secondary side of transformer:
• According to the effective load of all connected devices
• Line G (system potential) must always be fused
• Where required, line G0 (system neutral) also
7.2 Device-specific regulations
Among other aspects, the safety of devices is ensured by extra low-voltage power
supply (AC 24 V) as per SELV or PELV.
Electrical parallel connection of VAV Compact Controllers provided the required
operating voltage tolerance is observed. The voltage drops of the supply lines
must be taken into consideration.
When planning and installing room controllers and field devices with Modbus RTU
connection, the permissible cable lengths, power supply and topologies must be
followed. Planning should take into account possible future extensions of a plant.
Mechanical coupling of the devices is not permitted.
Do not open the actuator!
The device is maintenance-free.
Only the manufacturer may carry out any repair work.
Operating voltage
AC 24 V
Device safety
Electrical parallel
connection
Modbus wiring
Note
Warning,
maintenance