The H51q System Family
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4.3.9 Special Features of the Output Modules
All output modules have the following special features:
– To increase the availability the outputs of the safety-related output modules can be
switched in parallel without external diodes.
Decoupling diodes are already integrated on the module (see the corresponding data
sheets).
– No output voltage is generated if the supply voltage L- is cut at the output module.
– The connection of inductive loads can be done without using protection diodes at the coil.
However, it is recommended to connect a diode directly at the inductive load avoiding
noise voltages.
– The LED signaling the output status is controlled separately.
– The design of the cable plugs enables the two-pole connection of the actuators. Together
with a two-pole supply of the output module an earth fault detection will be simplified by
means of a totalizing current transformer.
The cable plugs are available in two specifications:
• L- in cable plug, one-pole with common L-
• L- in 2-pole type, 2-pole with L- per channel
see also chapter 10.13.6, “Description of the Order Code for Cable Plugs”, option P2
– No time-limited operation in case of a faulty output module.
4.4 System Voltage 24 VDC
HIMA systems will be connected to 24 VDC. The connection terminals are labelled with L+ and
L-. The power supply units made available by HIMA, e.g. the power supply PS1000, meet the
requirements according to CE for electrical safety and EMC.
All used power supplies must fulfill the requirements SELV (Safety Extra Low Voltage) or PELV
(Protective Extra Low Voltage). See also chapter 6.4.
The power supply units meet the requirements of the NAMUR recommendation NE 21 for the
safety during short-time voltage dips up to 20 ms.
For the supply of 24 V sources, which cannot guarantee a buffering during voltage dips of at
least 20 ms, the following measures must be taken in the H51q system family:
• decoupling of the power supply for the central units and
• noise blanking (parameterizable).
Note Due to the high inrush current of lamps the correct dimensioning of the
power supply units for lamp loads must be regarded.
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