Festo Checkbox Compact CHB-C-C, Manual

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2. Fitting and commissioning
2-11
Festo P.BE-CB-COMP-EN en 0211a
2.3.1 Selecting the power unit
The power supply for the Checkbox must fulfil the following
requirements:
– Voltage range: 24 V ± 15 %
– Output: 18 W with non-loaded outputs
In order to comply with the EMC limits, the Checkbox is
equipped with a filter for the operating voltage. Use a separ-
ate power unit for the Checkbox. Only in this way can the
fitted filter function optimally.
Warning
Use only power units which guarantee reliable isolation of
the operating voltages as per IEC 742/EN 60742/VDE 0551
with at least 4 kV isolation resistance (Protected Extra Low
Voltage PELV). Switch power packs are permitted, provi-
ding they guarantee reliable isolation in accordance with
EN 60950/VDE 0805.
By the use of PELV power units, protection against electric
shock (protection against direct and indirect contact) is guar-
anteed with the Checkbox in accordance with EN 60204-1/
IEC 204. Safety transformers with the adjacent symbol must
be used for supplying PELV networks. The Checkbox must be
earthed to ensure that it functions correctly (e.g. EMC).