HV-V2V for REGFGC3 type 7 chassis

Wednesday 10 Apr 2024, 11:00 → 12:00 Europe/Zurich

866/2-D26 (CERN)

Minute_Meeting_Type7HV-V2V.docx

Minute_Meeting_Type7HV-V2V.pdf

Subject 1

For the consolidation of the LHC RF converters, a REGFGC3 type 7 chassis will be used.

Julien and Stephane wanted to understqand what's the appropriate signal conditioning board to use with a REGFGC3 type 7 chassis for the conditioning of the signals coming from a LEM Hall effect current transducer and a High Voltage divider. 

In a previous application Julien used a V2V. For that he converted the current signal from the LEM into a voltage signal by useing the "Divisor module" board. He then connected the resulting LEM voltage signal to channel A of the REGFGC3 V2V board and the voltage divider directly to channel B of the REGFGC3 V2V board.

Miguel reccomended to use a revised version of the HV-V2V instead. The LEM current signal shall be routed to the current channel of the REGFGC3 HV-V2V board and the voltage divider directly to the voltage channel of the REGFGC3 HV-V2V board.

For this to work, HPM needs to do a new version of the HV-V2V in order to correct an incompatiblity issue with the I2V/V2V pinout.

The incompatibility is the folowing:

On the I2V, the current from the current output transducers arrives to the I2V on pins J1-C22, J1-C23 for channel B and J1-C28, J-C29 for channel A. Since on the HV-V2V channel A is a current channel, J1-C28 and J1-C29 should be used, as if it was an I2V. However on the HV-I2V this was not done. Instead, the pins used on the HV-V2V were J1-A28, B28, which are the same as used on the V2V for a voltage channel.

This must be corrected, in the following way:

• The current input on the HV-V2V board should use pins J1-C28 and J1-C29 (same as in channel A of an I2V)

• The voltage input for the HV-V2V board should use pins J1-B26 and J1-A26 (same as in channel B of a V2V)

 

This way, if we use HV-V2V on type 10 and type 7 REGFGC3 chassis, the signals that arrive from the SK_DCCT_A 12 pin BURNDY pins 5 and 6 and are routed in the type 10/7 to pins J1-C28 and J1-C29 of an I2V, will now arrive to the current channel of the HV-V2V and the signals that arrive from the SK_DCCT_B_VS 4 pin BURNDY pins 1 and 2 and are  routed in the backplane to pins J1-B26 and J1-A26 of a V2V, will now arrive to the voltage channel of the HV-V2V.

NOTE: in subsequent discussions it was requested by FPC that each one of the channels on the HV-V2V shall be able to receive the signals either from SK_DCCT or from SK_DCCT_VS. This is to allow the connection for example of a voltage LEM on the voltage channel which means the 12 pin BURNDY needs to be used to provide the +-15. For that, it will be included in the HV-V2V a short circuit between the pins c22 èb26 , c23èa26, c28èb28, c29èa28, which ensure signals still arrive to the desired channels irrespective of the connector used.

A few other modifications are necessary in the HV-V2V: 

• modification of C3 120pF è 25pF
• modification of burden resistors 1206 R19-R20 and through hole R10-R11 for more flexibility in terms of power and value

 

Subject 2

On the RPZEP converters, a LEM Hall effect transducer is used with an I2V 100A board. Relatively high offsets on these devices caused warnings due to IDIFF and Olivier had to use the calibration constants of the I2V to compensate for those offsets. the reason to use the LEM is basically down to cost and dimensions of the device. Miguel pointed out that it can be kept like this as long as we are aware that when replacing one of the devices a new calibration needs to be done since now the I2V and the LEMs are paired, due to calibration.

On the LHC RF converters a similar situation will happen. In that case, HPM reccomends to use an HV-V2V and use the current input of the HV-V2V for the LEM current signal and the voltage input of the HV-V2V for the voltage divider on the RF converter transformer tank. It is reccomneded to re-design that voltage divider and try to keep the source impedance from the divider below 10kR.

Stephane also asked about the best way to route signals from current measurement devices internal to commercial power supplies. Miguel replied that, if those signals are voltage signals, then a V2V can be used.