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DeltaV DIN-mounted Smart Switches High Temperature and Associate Alarms

Hi colleagues,

We have a number of the DIN-mounted smart switches VE6041 in our DeltaV system. Specifically, their model number is VE6041F05C1.  Since installation, we have received a number of hardware/device alarms associated with these switches, and from looking at their on-line control module, we see that the temp of the switches had exceeded the 50 degrees C (122 degrees F) setpoint.  The general internal cabinet's temperature (where the switches are located) is about 85 degrees F typically.  Occasionally, when the general temperature of the cabinet rises to about 95 degrees F, the high temp alarm situation of the switches occurs.  So what we have seen is that the temperature of the switch is consistently about 30 degrees F higher than the general internal temperature of the cabinets. In other words, if we want to bring the temperature of the switches down, the obvious way is to bring the general temperature of the cabinet down which is not simple for us at this point.

I have some questions:

1. Has anyone encountered this situation? I so, what measures did you take to alleviate it?

2. Is there a KBA or similar information about the high temperature of the switches from Emerson?  Is there a known issue with these switches? Is there a recommended way to install these switches? 

3. Our goal is to make sure we don't shorten their lives with constantly running hot.  We are looking at some internally mounted spot blower to provide more airflow over these switches.  What recommendation can you give us?

Thanks

3.  

ha nguyen

• 16 Apr 2024 4:27 PM
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5 Replies

• Andre Dicaire

  

  • 16 Apr 2024 7:19 PM

  There is confusion between the internal temperature reading and the Ambient operating temperature. The alert setting is relative to the ambient operating temperature, set at 50F. But the runtime temperature is an internal sensore that is heated by the Switch electronics. The temperature sensor will always show higher than ambient.
  
  In the Switch module, you can adjust the trip point for the Alarm. You can set this to higher value.
  
  The switches use convection air flow for cooling. The Ambient air should be within normal operating range, and 95F is well within that range. Compare the readings from all your switches and see if they have a consistent offset from ambient, say 30deg F. If the airflow around a switch is obstructed by wire ways (panduit) or located above heat sources like power supplies, you might see deviations between different switches. If a few switches are significantly hotter than the others, I would evaluate their installation for air flow.
  
  Once you've compared the actual values of the switches to ambient temps, you can determine what normal offest is for these switches. Say it is 30 deg F. Then set your trip point to reflect a problematic ambient air. Say max operating temperature is 140 F, you expect max 95, so a value of 110 would be abnormal. Set the Switche temp to 110 + Offset, or maybe 140 Deg F.
  
  Values above are examples. Monitoring the actual switch temperature is better than monitoring Ambient air. In normal operation, the switch temperature - offset approximates ambient temperature. Useful information. However, if airflow to the switch is obstructed it could overheat even when ambient temperature is "normal".
  
  Monitoring temperature is important if there is active temperature heating/cooling and if this fails, the cabinet temperature could climb or fall outside operating range leading to operational issues or product failure. If there is no active cooling, then ambient temperature changes are not "controllable". Monitoring the product temperature will always give you the absolute temperature that really matters regarding reliability.
  
  So you just need to adjust the smart switch trip point.

  Andre Dicaire

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• ha nguyen

  

  • 16 Apr 2024 8:54 PM

  In reply to Andre Dicaire:

  Thank you for your response, Andre.

  For all of our cabinets, we have seen a consistent delta of about 30 degrees F between the switches temp and the ambient temp (the ambient temp sensor is in the general area of the cabinet about 15 inches away from the area of the switches).  We suspect this is an airflow issue as you mentioned about obstructions.  As you can see in the picture, our switches are surrounded by Panduit (similar installation for all our cabinets). 

  I want to confirm first that there are no known issues concerning the high temperature detected by the switches (its electronics, manufacturer components, over sensitivity of sensor, etc.) before finding a resolution of increasing the airflow around the switch (which will be a challenge as you can see from the picture).  

  I absolutely agree with you about the product temperature that is crucial for reliability.  That's why at this point I must trust that this high temp we see is in fact accurate and find a solution.

  

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• Andre Dicaire

  

  • 16 Apr 2024 10:58 PM

  In reply to ha nguyen:

  These switches should have the extended specs of -40 to 70 Deg C or -40 to 158 Deg F. This is the Ambient temperature rating. The internal temperature will always ride above the ambient temperature. Your normal cabinet ambient temperature of 85 Deg F is well below the 158 deg F maximum rating for these switches.
  
  Your concern about long term effect due to heat is valid, but your situation is well within normal. The space around the switches, specifically below and above appears to be adequate. It is normal to see the internal temperature reading of the switch to be 30 to 40 Deg F above ambient.
  
  What is unfortunate is that the default trip level of the Switch is set to a reasonable ambient temperature limit, say 50 Deg C/ 122 Deg F. It needs to be offset to account for the internal temperature rise, which in my opinion means it should be set to 150 deg F, or 65 Deg C.
  
  My FP20 switches set at about 57 deg C or 134 F. The ambient temperature of the cabinet is warm at about 30 deg C, 86 deg F. Well below the max ambient rating of 70 Deg C. Your temperature readings are not alarming, so adjust your alert trip point to 150 Deg C.
  
  The same physics apply to the CIOC cards and their internal temperature indication. these will ride the ambient temperature by about 20 Deg C, plus or minus depending on total number of CHARMS. (the more CHARMS, the more heat is generated in the IO Card for the CHARM Power bus, but the offset stays fairly constant through the entire operating range. I've observed -32C to +45C outside air temperature, and the ambient vs internal temperature stayed within 21 to 22 deg C offset.
  
  I don't see any issue with your cabinets when you say the max ambient temperature may reach 95 deg F. No concern about spacing of panduit either. If your ambient temperature was north of 125 deg F, I might investigate if cooling is impacted by the conduit. It may not be a noticeable impact. There is space and panduit is slotted, and unless jammed full with wires, air still flows through it.

  Andre Dicaire

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• ha nguyen

  

  • 17 Apr 2024 2:33 PM

  In reply to Andre Dicaire:

  Thank you again for your input.  Thanks for taking the time to write.  It's quite comforting I must say.  

  The max ambient temp rating for the switch model we have is 60 degrees C (140 degrees F) per Emerson literature and it does state this is "Ambient Conditions".  Our average ambient temp in our cabinets is comfortably below the max from what we have seen so far.  It does seem counter-intuitive to have the default setpoint be without some expected offset, but then again I expect offset amounts will vary for different cabinets designs.

  Best regards. 

   

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• ha nguyen

  

  • 18 Apr 2024 3:28 PM

  In reply to ha nguyen:

  Just want to add this KBA (for those that may be interested) that I just received from our local Emerson partner.  It's supportive to the input from Andre.  Thanks again. 

  

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