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Variable air volume controllers
Checking the power supply
Checking the power supply
The ZTH-GEN offers the possibility of checking the AC 24V power supply (III safety extra-low
voltage) of the Belimo devices. Voltages >30V are not permitted!
Application e.g. Commissioning, troubleshooting in the event of a malfunction.
Measurement procedure
Equipment: ZTH-GEN, ZK2-GEN
Connection: – connect free wires of the ZK2-GEN to AC 24V.
• white on GND (connection 1 actuator/VAV controller)
• blue on ~
(connection 2 actuator/VAV controller)
• third wire (turquoise) do not connect
– Do not connect RJ11 plug to ZTH-GEN yet!
Start:
– Press the ZTH-GEN key (OK) while at the same time connecting the RJ12
plug
– Select Supply function with arrow key (
▼
)
End:
Disconnect ZTH-GEN RJ12 plug or end Configuration function (OK)
Display
Display
Supply
okay
AC 24V
VHW:
88%
Quality:
okay: AC supply in the division 19.2 ... 28.8V
AC value: measured AC voltage (accuracy ±1.0V insofar as VHW >95%)
VHW:
Relationship of positive to negative half-wave
The deviation of the positive half-wave value to the value of the negative half-
wave may not be too large. As a rule: positive HW / negative HW x 100 should
be >80%.
Explanation VHW
Possible problems
The following items influence the half-wave load:
• Transformer too small in its dimensions
• long signal cable length from transformer to VAV controller
positive HW
negative HW
