Chapter 4 Class 1 (Cl1) Cable - Parker H Series Installation & Service Instructions Manual

Class 1 (CL1) cable
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Determine Power Requirements
In this chapter, we describe two methods for determining your system's power
requirements:
• the look-up method
• the full calculation method
Try the look-up method first, then move on to the full calculation method if
you cannot meet your configuration requirements.
You must consider two areas when powering output
IMPORTANT
devices using the DeviceNet power supply:
• (1) Wide DeviceNet voltage range of 11-25V dc
• (2) Noise or transient protection at each device
You must calculate a worst-case situation, and maintain
voltage within the 11-25V dc range on all segments. This
can be accomplished using diodes or other similar
techniques. See Appendix B, Powering Output Devices, for
more information.
Per NEC specifications for a Class 1 circuit (see NEC Article 725), the energy
at any point in the circuit is limited to 1000 VA. A Class 1 circuit requires that
the cables used must have jacketing with 600V isolation and pass the CL1 burn
test.
The DeviceNet specification indicates that the power source must be a
regulated maximum of 24V dc, and the power circuit be limited to 8A.
Applying this to a Class 1 circuit running at 24V dc, a DeviceNet-certified
cable with a 600V jacket isolation rating meets all requirements to be used in a
Class 1 circuit. So, based on the DeviceNet specification, the cable's power-
carrying conductors are sized for an 8A maximum load.
Chapter
Publication DNET-UM072C-EN-P - July 2004
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