Dear experts,

we have Bailey infi-90 DCS System ,its termination Units for digital inputs from field are connected from a 24VDC floating power supply(-12/+12 VDC). suddenly many modules failed and we got a ground fault and burn cards on their -ve side power supply and we found the power supply became +11/+35 VDC instead of -12/+12 VDC. the power supplies are four each are connected together in redundant configuration.

we found one of these 4 power supplies not working and I expect it may be the cause of the DCS module failures as there is high power came to the -ve side of the DCS Termination units but can this happen for a floating power supply who suppose to give -12/+12 VDC to give for example +11/+35??

this problem caused many DCS digital input channels to fail on short circuit and the high +ve power to go to the -ve side through the short circuit defect DCS digital input module and the closed field dry contact.

can Infi-90 DCS digital input channels failed on short circuit??
also can floating power supply (-12/+12)fail giving high +ve power on the -ve side???

thank you ...

 

Dear Honywepco,

If you need any Infi90/Symphony spare part to replace your faulty units, please feel free to contact us (baileyparts [at] gmail.com). We provide competitive and cost effective latest new model (BRC300/IMMFP12 and more) and all the obsolete model (IEPAS01/02 and more).

Rdgs,
BaileyParts [at] gmail.com

 

>In answer to your questions:

> can Infi-90 DCS digital input channels failed on short circuit?? <

Input channels on Infi90 cards do not fail from a short across the input, the typical cause of failure that you described is a voltage on the input exceeding the range configured for that input, for example your inputs would be configured for 24 VDC; a voltage on the input channel greater than about 32vdc would cause input failure.

> also can floating power supply (-12/+12)fail giving high +ve power on the -ve side??? <

It's possible for a power supply to have a failure where the voltage output would be as you described but not likely, with the floating power system the +ve is 24vdc and -ve is com in relation to the supply since it is floating under normal conditions you see the +12/-12 when compared to ground. From past experience it sounds like a wetting signal wire got shorted to a higher voltage source.

If you have other questions on the infi90 system you can email me at wkline [at] rdicontrols.com

Bill