12
Ionization Gauge Instruction Manual - 274026 - Rev. B
2.3
Electrical Connections
Do not use gauge cables with exposed conductors such as alligator clips.
All gauge pins must be covered by connectors or by pin covers (insulation).
Gauge cables should be firmly clamped to the vacuum station to provide
strain relief and ensure that minimal strain is transmitted to the gauge pins
if there is motion between the gauge and the gauge controller.
If a resistance heated (I
2
R) degassable nude gauge is being used with an
electron bombardment (EB) controller, be sure that the unused grid pin on
the gauge is covered (insulated).
Figure 2-1 lists the two types of electrical connectors available on the nude
gauges (near the botttom of the chart).
Figure 2-2 illustrates the pin connections for Series 274 B-A gauges.
Figure 4-1 illustrates the nude gauges with and without the strain relief for
the electrical connector.
2.4
Grounding Requirements
All conductors in, on, or around the vacuum system that are exposed to
potential high voltage electrical discharges must either be shielded at all
times to protect personnel or must be connected to earth ground at all
times.
Connect a heavy duty #12 AWG or larger ground wire from the ground lugs
on the backs of the Power Supply and the Control Unit to your facility
grounding electrode system. This will provide an earth ground for the Power
Supply and for the Control Unit in the event either the interconnect cable
or power cable are not in place. Do not connect the ground lug to the
vacuum system or other component. Connect it directly to the facility
grounding system such as a grounded outlet box or a grounded copper
water supply pipe. Do not rely on small metal water lines to ground a
component. Someone may replace the metal tubing with plastic tubing thus
unwittingly causing a potentially dangerous situation.
Provide a connection to ground for other instruments with electrodes in the
vacuum system possibly exposed to high voltage electrical discharges.
Provide a connection to ground for each ungrounded metal component in,
on or around the vacuum system, including the gauge envelopes, which
personnel may touch and which can potentially be exposed to high voltage
electrical discharges within the vacuum system. For example, a metal bell
jar resting on an organic O-ring must be connected to ground if an
ionization gauge is to be used or if other high voltage sources are present in
the vacuum system.
