Monitoring I/O supply status

Hi all,

I'm just wondering what you throughts are towards monitoring the status of the power supply to individual I/O cards on a rack. For instance on 32 way input cards I generally split the supply into 2 fuses.

The problems come when one of your fuses fails, how do you diagnose the failure?

In the past ive wired back a feed from each of the fuses into an input card, which gives you a concise alarm condition of individual fuses but depending on the number of I/O cards, you can start using up a lot of I/O for panel diagnostics. Ive also done it using a relay per fuse with the outputs of all the relays wired in series to give you a common healthy signal, which isn't as concise but still gives you a fault signal but conversely is an expensive solution.

What's your experience and solution for monitoring supplies?

Cheers,

Lee

I have used Fused Terminals with LED Light on the fuse. Pretty easy to diagnose when fuse goes.

I typically split my I/O card feeds into groups of 10, with each group being fed by a common fuse. Handy from a number grouping standpoint on the terminal blocks, and it makes it a little transparent to follow if an entire group is not responding. As far as actually monitoring the power supplies, I usually monitor the PS voltage and current. This takes a CT for some power supplies, but we have pretty much standardized on the Kepco rack mounted units, which have a voltage and current monitoring option. Either way, you can see the overall staus of the supply before chasing fuses.

+1 on the LED indicator fuseholders... a little more expensive, but no test equipment needed!

Hi thanks for your replies so far. Apologies for responding late after the fact. I do like the indicating fuse idea but I need something displayed on the hmi to tell the engineers to look in the panel in the first place. In the applications I have its normal for the inputs in particular to be either on or off so I cant look for an input to be in the wrong format to generate a fault.

Any other ideas?

Cheers, lee

RheinhardtP said:

I have used Fused Terminals with LED Light on the fuse. Pretty easy to diagnose when fuse goes.

Click to expand...

What type ?
And cost vs cost of a regular circuit breaker ?

How about a reversed biased diode from the input power of each card to a common 24 VDC input point.
The input pont would be held to +24 thru a 100K resistor.
If any one card lost it's power the common point would be pulled down to zero turning off the input to cause an alarm.
I'm sure you could include an LED to display which card was lost.\

I'm also in favour of having one fuse for each module or 2 per module where they are divided into 2 groups of 8.
If the project budget can handle it the little circuit breakers that pop out to indicate the trip condition are even better

Roy Matson said:

How about a reversed biased diode from the input power of each card to a common 24 VDC input point.
The input pont would be held to +24 thru a 100K resistor.
If any one card lost it's power the common point would be pulled down to zero turning off the input to cause an alarm.
I'm sure you could include an LED to display which card was lost.\

I'm also in favour of having one fuse for each module or 2 per module where they are divided into 2 groups of 8.
If the project budget can handle it the little circuit breakers that pop out to indicate the trip condition are even better

Click to expand...

Hi roy, thats the kind of thinking I'm after. My electrnics is s little rusty. Any chance of a quick diagram?

Many thanks lee