Telemark TT Cheetah Series Power Supply Instruction Manual
12
Connecting to Building Steel
The best method known for grounding the E-beam is to tie the ground bar to building steel as
close as possible using the appropriate grounding strap (varies based on the distance - see
details below). One must verify that the building steel has a good connection to ground for
this to be a viable solution. Be sure to remove any paint, rust, etc from under the connection
point to the building steel.
Because the connection is for an RF ground, surface area is more important than cross-
sectional area. It is critical to have a wide surface area of connection between the grounding
strap and the building steel.
Distance Between E-Beam Chamber
and Grounding Point
Minimum Recommended Strap/Cable
< 10 Feet « 3 meters)
#6 Gauge or larger gauge copper cable
10-20 Feet (3-6 meters)
#4 Gauge or larger gauge copper cable
20-60 Feet (6-18 meters)
2 inch by .035 inch thick copper strap
> 60 Feet (> 18 meters)
Contact Telemark for recommendations
Table 4-1: Ground Strap Size
When in doubt, always go with the larger ground connection. You can never have too good of
a connection!
Do not use braided wire. Be sure that the connection is made to clean metal.
The power supply is connected to ground using the HV cable’s shield connection. The
power
supply may sustain major damage if power is applied before the ground is connected.
High Voltage
Use decals or other warning labels on the high voltage shield, at the front of the E-beam
chamber and on the door to the room to provide warning that lethal voltages are present. Do
not put any part of the body under a chamber while a source is running. Always use a
grounding hook as a matter of habit before touching any potentially high voltage area, even
when power supply is off. Always keep one hand in a pocket. Always maintain a respectful
fear of high voltages: familiarity does not make high voltages safe.
Ground Connections
In addition to the critical building (earth) ground described above, there are 6 other ground
leads that will attached to the ground bar on the E-beam chamber:
1. Source Transformer Box - connected using 6 AWG gauge wire
2. E-beam power supply - connected using 6 AWG wire
3. Safety cover over high voltage feedthrus - connected using 12 AWG gauge wire
4. Sweep controller - connected using 12 AWG gauge wire
5. TT-Controller - connected using 12 AWG gauge wire
6. Sweep cable ground connection - connected using 12 AWG gauge wire
There is not a required order for the above; simply connect each ground lead securely to an
open ground lug location on the ground bar. Ensure connections are secure prior to turning
on the power to the E-beam. Operating without one or more grounds properly connected may
cause damage to equipment or even harm to the operator.