24VDC Power Supply Filter for RLM01

I have a question about RLM01,I noticed there is one chapter in RLM01 manual regarding application for ships and maritime systems,a 24VDC power supply filter is required for .

So my question is why S800 IO and controller don't have such requirement?does it mean S800 IO and controller is more robust in terms of EMC?

Now we have a project in marine,and the IO communication is disturbed by unstable power supply,we monitored strong noise added on the 24vdc voltage, so can we use this 24VDC power supply filter for S800 IO as well?

Statment from RLM01 manual:


RLM01 is certified for applications on ships and maritime systems by the Germanic
Lloyd (GL). To meet the increased requirements regarding EMC and overvoltage,
RLM01 must have one or two "24 VDC power supply filters (surge)" depending on
the supply (single / redundant). The supply of several RLM01 behind one filter is

not admissible. The max. length of the lines between filter and RLM01 must not
exceed 1 m. Possibly needed fuse elements have to be arranged before the filter. The
electrical connection to ground potential is effected via the module attachment as
with RLM01. The following example shows the interconnection in case of a
redundant supply of RLM01. For a single supply of RLM01, the L2+ terminal has
to be bridged with the second L1+ terminal.


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WeiFeng Cao   

asked 5 years ago



That's because assumed you are using ABB SD82x power supply and mains voltage variations are not exceed specified limits. However, if your system with S800 and AC 800 supplied by different way (e.g. you have 24V DC network inlet, or using another power supply unit) you need to install filter (in case you are suffer surges or noises in LV) - either mains or at LV inlet in order to provide stable power for S800 and AC 800M.


answered 5 years ago


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I have been working with the S800 I/O's in the Marine Industry and we did not face such kind of EMC problems yet. I suppose that the fluctuating power supply problem can be because of improper earthing as the S800 I/O's and even the ABB Power Supply is EMC Compliant.

The earthing for the DC power distribution can be checked in the following way:

System DC power distribution is via fuses/MCBs and the 0v return to the power supply modules is referenced to the PE bar, this is done to allow any fault current to flow directly to earth (in the event of a +24v fault to earth in the system). This connection does offer limited EMC (low frequency) advantages, if possible better EMC performance can be achieved by connecting the power supply unit 0v directly to the cabinet chassis using a short link.


answered 5 years ago


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