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Pixel Power Supply Response Measurement Lalith Perera - Univ. of Iowa Carlos Florez , Simon Kwan, Charles Newsom, Chris

Response of the CAEN power supply to transient currents Response of the power supply to remote shut down. . Pixel Power Supply Response Measurement Lalith Perera - Univ. of Iowa Carlos Florez , Simon Kwan, Charles Newsom, Christian Veelken. CAEN Power supply overview.

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Pixel Power Supply Response Measurement Lalith Perera - Univ. of Iowa Carlos Florez , Simon Kwan, Charles Newsom, Chris

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  1. Response of the CAEN power supply to transient currents • Response of the power supply to remote shut down. Pixel Power Supply Response MeasurementLalith Perera - Univ. of Iowa Carlos Florez , Simon Kwan, Charles Newsom, Christian Veelken L. Perera

  2. CAEN Power supply overview SY2527 system mainframe Can install six A1676A branch control cards A1676A branch control card Controls one E4000 crate E4000 crate Accommodates 8 power modules CAEN E4603 power module Each unit has two independent power units Two low voltages 2.5V, 1.75V (remotely sensed voltage control, up to 6V at the supply) Two high voltages. L. Perera

  3. scope CAEN A4603 48V Cable ~40m Load CAEN SY2527 Pulse generator • Preliminary testing to get familiar with using the power supply with the MSC cable for the system test • Make sure that power supply meet system requirements and behave well with remote sensing: • Current fluctuations changes the voltage drop across the supply cable resulting fluctuating voltage at the load. Objective L. Perera

  4. We used a 40m length of MSC cable • Six 4mm2 cables for LV • 4 for 2.5 V • 2 for 1.75 • Resistance of each cable 0.005W/m • Cables for sense wires and HV CMS pixel power cable (MSC) L. Perera

  5. switching transistors Jumper switches resistor elements • Test Load • Six resistors ~1.6W (connected through • jumper switches - up to 8A current) • Two 0.1W connected through switching • transistors (FET) (2A pulse current) Test Setup L. Perera

  6. voltage at the load • No observed oscillations • Voltage drops by ~ 0.5V when load change by 2A. • recovery time of the power supply • 2.5V ~50 ms, 1.75V 100 ms • There are small (50mV) spikes at ~ 80kHz likely to be coming from from switching in the power supply pulse current control pulse 2.5V 1.75V Results L. Perera

  7. after adding 13mF capacitor response to 1ms pulse • Voltage fluctuation can be lowered by adding decoupling • capacitors near the load • However in the real detector load is distributed, so capacitors at • each ROC should take care of the fluctuation L. Perera

  8. CAEN power supply is controlled by the DCS computer so can be turned on/off through DCS. It is software controlled so would to be too slow for an emergency shut down. • There are two control inputs to SY2527 to turn off all channels. • KILL: input for a TTL/NIM signal • “ The KILL input signal, sent through the relevant connector, allows to switch the channels off at the maximum rate available, regardless of the Ramp-Down or other parameters.” • INTERLOCK: close/open circuit input • “The INTERLOCK condition allows to switch off simultaneously all the channels, similar to the KILL command” Remote Shut Down L. Perera

  9. Pulsegenerator power supply KILL load scope From PLC INTERLOCK power supply relay load scope 5v Test setup to measure KILL response time Shut Down Response Time Measurement Test setup to measure INTERLOCK response time L. Perera

  10. KILL Response time Power Digital Power Ana. 68ms 18ms 36ms Results: KILL 40ms 96ms 27ms Response time to KILL changes from few ms to ~100ms L. Perera

  11. INTERLOCK 36ms 42ms 68ms Power Digital Power Ana. • Measured INTERLOCK response time is tens of ms and varies • It could be that both KILL and INTERLOCK is activated by software • So depending on where it occurs in the control loop of the • power supply it gives a different response time. • This needs to be verified with CAEN. INTERLOCK Response Time L. Perera

  12. Power supply behaves well to transient currents with the CMS MSC cable. No oscillations observed. • Remote sensing time constant of the supply voltage is about 25 ms. • There are two remote hardware shut down modes (INTERLOCK, KILL) available. Both have response times in the order of tens of ms Conclusions L. Perera

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