VDC HV control

Relay Box with 8 relays (channels) controlled by RPi board is used to limit trip current and prevent trips for VDC high voltage line during HV on/off operation.

Two of them have been installed in Left and Right HRS at the end of March, 2017.

• Left HRS:

  name: rpileft 
  IP: 129.57.164.27
  passwd: same as for rpi8

• Right HRS:

  name: rpiright 
  IP: 129.57.164.53
  passwd: same as for rpi7

Relay box consists of 8 relays and 8 resistors with 68Mohm nominal. Resistor is connected in series between output of hv channel and VDC hv line, or shortened by relay.

RPi board is used as TCP/IP server to control relays by commands from clients. RPi board in HV crate (rpi8(left), rpi7(right)) runs 'shim-server' to control modules in crate.

Shim-server will send commands to relay box server to switch relay ON (closed, shortened resistor) or OFF (open, resistor in).

Shim-server checks commands/responses from GUI to hv channel that connected to VDC. The next logic will be used by shim-server to control relays :

• commands: HVON, HVOFF, demand voltage (DV) set, enable/disable channel (CE), channels status (ST>1) ---> relay is OFF (open, resistor in) for this channel.
• channels status (ST==1) --> relay is ON (closed, resistor out) for this channel.
• initial state of relay RPi board after power on is all relays OFF (open, resistor in).

Command format for relay box server is the same as used by LeCroy HV system (examples):

• set relay channel #1 to ON (closed)

LD S0.1 RLY 1

• set relay channels #0,#2 to ON (closed) and channels #1,#3-#7 to OFF (open)

LD S0 RLY 1 0 1 0 0 0 0 0

• get status of all relays channel (1 - is ON, 0 - is OFF)

RC S0 RLY

Hv module for VDC will have one more property column 'RLY_en' in Java GUI, that shows status of relay box channels (0 - relay is OFF, 1 - relay is ON).