1. UKDC2 Stavelet with Tandem Converters Peter W Phillips

2. Gratuitous Photograph Note “suction cup” marks -Does not affect IVs -Is this an issue? 2

3. 18/12 3PG @1fC, 200V, H0 AC strip bias 18/12 same H1 only 18/12 same H0 only 18/12 same H0 now DC strip bias 3

4. Try some things! 2440-3 Add Cu shunt to H1 converter output H0 gnd rise 23mV H1 gnd rise was 40mV, now 5mV No significant change 2440-12 Pull H1 M shunt bonds No significant change 2440-15 Remove BCC edge referencing bonds Eliminate possible I loop No significant change 2442-1 Pull H0 backplane contact Actually lift soldered wire H0 Rbpc ~100ohm -> open H1 Rbpc ~20 ohm H0 slightly worse H1 much better (see over) H0 H1 4

5. GND shunt added to H1 converter 1 backplane contact @ H1 only Pull BCC edge reference Bonds @ H1 edge Pull M shunt bonds On hybrid H1 5

6. Try more things! 2442-4 Put H0 backplane contact back AC only (5k1 pulled) H0 slightly better H1 slightly worse 2442-7 Reduce H0 Rbpc to 1 ohm AC only H0 no significant change H1 MUCH worse 2442-10 Add third backplane contact AC only H0 MUCH worse H1 slightly better 2443-2 Remove third backplane contact & Refit 5k1 resistor (actually 4k99) So now DC Similar to (2) above Cu tape stuffed under sensor & soldered to existing contact Cu tape stuffed under sensor, soldered to 10uF HV cap and thence to H1 GND H0 H1 6

7. 3 backplane contacts 2 x AC, 1x DC 2 backplane contacts 2 x DC (1ohm, 17 ohm) 2 backplane contacts 1 x AC (1ohm), 1 x DC 2 backplane contacts 1 x AC (100ohm), 1 x DC 7

8. 20/12 3PG @1fC, 200V,20/12 same H1 only20/12 same H0 only Single Backplane Contact @ H1 8

9. What’s going on? The HV filter cap on each hybrid bypasses the sensor backplane to the local ground A single contact typically works better than 1 – Suggests GND on the two hybrids are not sufficiently similar After this – Referencing bonds at H1 BCC edge were restored – Referencing ties improved a little – Set for single backplane connection (@H1) 9

10. What next? DC-DC Fan Club 10

11. DC-DC Fan Club Hybrid/Column SP ReferenceFANS ONFANS OFFFANS ON 0_0 630659669666 0_1 605632637631 1_0 641623631627 1_1 656660670669 Mean 633644652648 H0 Temp 22293028 H1 Temp 22303130 All columns go up when fans turned off, and back down when fans turned on. -> consistent with expected dENC/degree given accuracy of temp data? 11

12. What Next New chiller order in progress with Positive Displacement pump – Should eliminate dT between pipes – Should allow slightly lower temperature operation too One Wire T sensors in hand for extra T measurements – DC-DC converter temperatures Can we get hold of two single DC-DC units? – Either add module with separate converters, then upgrade to tandem for direct comparison with same hookup – OR Remove existing tandem and service existing module with two single converters 12

13. BACKUP

14. UKDC2 has been fitted with module LIV 8 This is the single module test result (SP) taken before assembly Note that high current / noise bumps develop in H1 above 190V So all runs taken at 190V after training SINGLE MODULE REFERENCE DATA 14