Precautions for limiting static damage to electronic equipment at Halley.

Most commercial equipment for use indoors is safe without modification. Home-made equipment outside should be thought about rather more carefully, and the FAGE container should be equipped with the first 3 points of item 1. These precautions are of greater relevance for instruments spending a winter at Halley although obviously are of interest to everyone. For more information, please contact Howard Roscoe.

• 1. Working indoors for repair and maintenance purposes:
• floors in labs should be anti-static (as in CASLab)
• use anti-static mats on benches  (as in CASLab)
• use earthing wrist straps.
• remove synthetic overclothing (skidoo suites, fibre-pile jackets) as you enter the lab
• consider antistatic slippers, rather than socks or liners (bare feet in summer ?)

• 2. Indoor apparatus:
• connect all cases and racks to mains earth
• where outdoor cables and insulating tubes enter the building, wrap copper tinsel round and connect to mains earth
• people are the main problem, observe practices in item 1 above
• re-discharge yourself on a rack before touching apparatus, or computer keyboards or screens

• 3. Outdoor apparatus:
• ensure all cases, internal power voltages, and 0V lines have a leakage path to each other and to mains earth, rather than being fully isolated.  Use 1 or 10 MOhm resistors in a star pattern  -   this should be standard practice to guard against RFI
• use external data and power cables with shields connected to mains earth
• I/O connections should have a heirarchy of precautions depending on the perceived susceptibility:
• • (a)  have a leakage path to 0V via a 1 or 10 MOhm resistor
  • (b)  add an R-C-R filter, as for RFI protection; if sensitive to R in series, use HF chokes
  • (c)  put a high-speed Zener diode across the C in the filter
  • (d)  use optocouplers so that discharge cannot proceed to internal circuitry (although the coupler may be damaged)