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Conference netcad::hub_mgnt

Title:	DEChub/HUBwatch/PROBEwatch CONFERENCE
Notice:	Firmware -2, Doc -3, Power -4, HW kits -5, firm load -6&7
Moderator:	NETCAD::COLELLADT

Created:	Wed Nov 13 1991
Last Modified:	Fri Jun 06 1997
Last Successful Update:	Fri Jun 06 1997
Number of topics:	4455
Total number of notes:	16761

602.0. "DH900 Power CUTOUTs with DEXUX-FA Installed..?" by CSC32::BLACKMER (Ralph Blackmer CSC/CS/IISG Netsupport) Mon Jan 10 1994 14:49

I just received a somewhat alarming question on a call Nancy Henderson took from
our queue today. It appears this customer has a DH900 that is configured with a
DB90, a DR90FL and 1-3, terminal servers, in an office environment, which
completely loses power when they have a DEXUX-FA cover installed over the
options.

It appears it overheats display a Yellow then Red condition and then a complete
shutdown occurs. It can be powered backup once some time is alalowed for the
unit to cool off. This looks much like the DH90 situation that has already been
addressed and resolved. Are we aware of any problems when these are covered up?

I will get additional details if necessary but wanted to raise a flag here.

Ralph B.

T.R Title User Personal
Name Date Lines

602.1 Thermal Testing of DH900 with cover CONSLT::THAYER Fri Mar 04 1994 15:36 87

T.R	Title	User	Personal Name	Date	Lines
602.1	Thermal Testing of DH900 with cover	CONSLT::THAYER		`Fri Mar 04 1994 15:36`	87
	Below is a report of some thermal testing I did for a DEChub 900 enclosed in a proposed cover. It shows a very modest increase in component temperature due to the stagnating effects of the cover. The configuration tested was typical, drawing approximately 50% of maximum power. The cover tested was a modified version of the "pin hole" cover used on the DH90. It was double length and had some significant vents punched in the top. The bottom, if I recall correctly, was open, or maybe had the same open punch pattern as the top. I'm not part number savvy, so I'm not sure what the DEXUX-FA cover is. If it is the DH90 "pin hole" cover, then I am not surprised that it drove a DH900 into thermal shutdown. With no opennings on the top and only pinholes on the front, it would constrict airflow. That cover was originally designed with vents in the top, but somewhere along the line some genius took them out as a cost cutting measure. Mike Romm is the person to ask about covers for the various hub products. CONSLT::Romm DTN 226-6181. John Thayer Thermal Engineer ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 24 November 1993 Mike, The following temperature data from a DETMM Maxmodule and a power supply confirm that the vents in your ONEhub cover do not significantly impede cooling airflow for a system. The system measured had 5 DETMM Maxmodules in slots 4-8 and 3 Minmodules in slots 1-3. There were 2 power supplies in slots 1 and 3. The total system has running at about half of maximum power, 200W DC. Under these conditions the DETMM in slot 7 and the power supply in slot 1 ran, on average, less than 2�C warmer with the cover installed. The test was conducted in normal room temperature. I would expect that at high ambient with the fans tripped up to high speed, the increment in temperature would be even less. An installation at maximum power would likely run 3-4�C hotter with the cover. This incremental increase in temperature is modest and will have minimal long term effect on product reliability and functionality. Thanks for paying attention to details of the design which effect system cooling. John Thayer ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ONEhub COMPONENT TEMPERATURE RISE ABOVE AMBIENT, �C As Is With Cover POWER SUPPLY Slot 1 D1 25.7 27.0 Q200 34.3 36.3 D300 38.1 39.6 5V Conv HS 24.9 26.2 15V Conv 23.6 25.5 Exhaust Rear 7.7 10.6 Exhaust Front 11.0 12.7 DETMM Slot 7 E42 35.8 37.5 E64 33.8 34.8 E116 38.9 40.3 INLET AIR Slot 5 1.0 3.5 Slot 6 1.0 3.3 Slot 7 1.4 3.1 Slot 8 1.8 3.9 EXHAUST AIR Slot 5 4.8 6.1 Slot 6 4.4 5.8 Slot 7 6.6 7.7 Slot 8 4.3 4.6

Below is a report of some thermal testing I did for a
DEChub 900 enclosed in a proposed cover. It shows a very
modest increase in component temperature due to the
stagnating effects of the cover. The configuration tested
was typical, drawing approximately 50% of maximum power.
The cover tested was a modified version of the "pin hole"
cover used on the DH90. It was double length and had some
significant vents punched in the top. The bottom, if I
recall correctly, was open, or maybe had the same open
punch pattern as the top.

I'm not part number savvy, so I'm not sure what the DEXUX-FA
cover is. If it is the DH90 "pin hole" cover, then I am
not surprised that it drove a DH900 into thermal shutdown.
With no opennings on the top and only pinholes on the front,
it would constrict airflow. That cover was originally
designed with vents in the top, but somewhere along the
line some genius took them out as a cost cutting measure.

Mike Romm is the person to ask about covers for the
various hub products. CONSLT::Romm   DTN 226-6181.

				John Thayer
				Thermal Engineer

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
					24 November 1993


Mike,

The following temperature data from a DETMM Maxmodule 
and a power supply confirm that the vents in your ONEhub 
cover do not significantly impede cooling airflow for a 
system. The system measured had 5 DETMM Maxmodules in slots 
4-8 and 3 Minmodules in slots 1-3. There were 2 power 
supplies in slots 1 and 3. The total system has running at 
about half of maximum power, 200W DC. Under these conditions 
the DETMM in slot 7 and the power supply in slot 1 ran, on 
average, less than 2�C warmer with the cover installed.
The test was conducted in normal room temperature. I would
expect that at high ambient with the fans tripped up to 
high speed, the increment in temperature would be even less. 
An installation at maximum power would likely run 3-4�C 
hotter with the cover. This incremental increase in
temperature is modest and will have minimal long term
effect on product reliability and functionality.

Thanks for paying attention to details of the design
which effect system cooling. 


				John Thayer


++++++++++++++++++++++++++++++++++++++++++++++++++++++++

   ONEhub COMPONENT TEMPERATURE RISE ABOVE AMBIENT, �C

			As Is	With
				Cover
   POWER SUPPLY Slot 1
	D1		25.7	27.0
	Q200		34.3	36.3
	D300		38.1	39.6
	5V Conv HS	24.9	26.2
	15V Conv	23.6	25.5
	Exhaust Rear	 7.7	10.6
	Exhaust Front	11.0	12.7

   DETMM Slot 7
	E42		35.8	37.5
	E64		33.8	34.8
	E116		38.9	40.3

   INLET AIR
	Slot 5		 1.0	 3.5
	Slot 6		 1.0	 3.3
	Slot 7		 1.4	 3.1
	Slot 8		 1.8	 3.9

   EXHAUST AIR
	Slot 5		 4.8	 6.1
	Slot 6		 4.4	 5.8
	Slot 7		 6.6	 7.7
	Slot 8		 4.3	 4.6