1. Slide 1UCSB CMS Weekly Status MeetingCMS 4-Hybrid Test System Sam Burke EE UCSB 4-Hybrid Thermal Test System Status Peltier T/E Element Degradation 28 February 2005

2. Slide 2UCSB CMS Weekly Status MeetingCMS 4-Hybrid Test System Sam Burke EE Peltier Failures Five peltier thermoelectric units have degraded over the past year. à February 2004 UCSB (overheated) à August 2004 UCSB(overheated) à February 2005 UCSB(unknown cause) FermiLab(unknown cause) CERN (gradual degradation) Units exhibited reduced thermal efficiency resulting in longer hybrid test cycle times à 65 min vs 40 min Replacing with new units restores short thermal cycle time.

3. Slide 3UCSB CMS Weekly Status MeetingCMS 4-Hybrid Test System Sam Burke EE Peltier Resistance Changes Degraded Peltier Units exhibit increased electrical resistance (4-12 amp range) à New Unit: 2.02 ohms à Old Unit (ser No 12): 3.00 ohms à Old FermiLab Unit: 5.0 ohms

4. Slide 4UCSB CMS Weekly Status MeetingCMS 4-Hybrid Test System Sam Burke EE Volt-Ampere Data

5. Slide 5UCSB CMS Weekly Status MeetingCMS 4-Hybrid Test System Sam Burke EE

6. Slide 6UCSB CMS Weekly Status MeetingCMS 4-Hybrid Test System Sam Burke EE Heat Exchange Cooling Water Flow Rates à 4 L/m suggested by Supercool à 1.3 L/m current use Measured cooling water exchange rate à 6 deg C at 1.3 L/m at full power

7. Slide 7UCSB CMS Weekly Status MeetingCMS 4-Hybrid Test System Sam Burke EE Temp Rise Calculation Hybrid Test Chamber Heat Transfer Calculation à Q=mcΔT à Q= heat = P*t=400 watts*Time = 400 J/s*1 s à m=mass of water = 1.0 L/min*σ /60 s/min –= 1/60£*1000cc/£*1g/cc=16 g à c=Specific Heat of water = 4190 J/kgK à ΔT=[Tout-Tin] deg C à ΔT=Q/mc=400J/(4190J/kgK*.016kg)=5.9 deg C rise

8. Slide 8UCSB CMS Weekly Status MeetingCMS 4-Hybrid Test System Sam Burke EE Peltier Failure Mode Degradation of thermoelectric element due to overheating à Nominal Input Power = (24v*12A)=290 watts à Current Usage = (24v*14a)= 336 watts (+16%) à Future Usage = (20v*10a)= 200 watts (-40%) It is now not possible to power up Peltier element without cooling water flow, even with a PC failure.

9. Slide 9UCSB CMS Weekly Status MeetingCMS 4-Hybrid Test System Sam Burke EE Current Interlocks Current Peltier Interlocks à 80 deg C thermal switch on unit à Software has peltier current locked to water flow à Hardware flow interlock (recently installed)

10. Slide 10UCSB CMS Weekly Status MeetingCMS 4-Hybrid Test System Sam Burke EE New Sensor Interconnect with Peltier Hardware Interlock

11. Slide 11UCSB CMS Weekly Status MeetingCMS 4-Hybrid Test System Sam Burke EE Plans Have degraded units refurbished rather than scrapped. à New unit $400 ea à Refurbished unit $120 parts and $40 labor Limit Maximum Power Levels à Voltage limit of 24 vdc à Current limit from 14 to 10 adc (17% reduction) –CERN has been using 10amp limit for last year –FERMILAB has agreed to 10 amp limit –UCSB should use this limit, Time=+1min on cycle