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Page 20
Safety Interlock
A safety interlock or secondary ground sense circuit is incorporated into the Terranova® 752A to
disable high voltage operation when open. The safety interlock circuit is completed via external
leads available on most Duniway ion pump cables. The external leads must properly connect the
ion pump body to the respective GROUND SENSE stud (see
on page 5) to complete
the safety interlock circuit and enable high voltage operation for the channel. High voltage output
will be disabled if an open circuit or ground fault is detected. Both the HV INTERLOCK OPEN and
selected pressure unit LED of the channel will illuminate if the corresponding safety interlock
circuit is open. To restart high voltage operation, user must correct the grounding issue.
lists various ground sense connection conditions and respective effects on high voltage operation.
A redundant ground connection, either intentional or unintentional, between the control unit
and ion pump may circumvent the safety interlock feature. User should correct any grounding
issues to ensure safe operation. A potential (unintentional) redundant ground may occur through
chassis contact with the ion pump or vacuum system ground when both the ion pump and
Terranova® 752A are mounted on the same conducting rack or cart.
Case
Primary
(Cable shielding)
Safety
Interlock
Redundant
High voltage
operation
1
N
N
N
OFF
2
Y
N
N
OFF
3
N
Y
N
OFF
4
N
N
Y
OFF
5
Y
Y
N
ON
6
Y
N
Y
OFF
7
N
Y
Y
ON
8
Y
Y
Y
ON
Under no circumstance should the secondary ground lead be
connected directly to the Terranova® 752A case. This would defeat
the protection provided by this safety feature and may cause serious
injury or death
WARNING!
Table 3.
Terranova® 752A ground sense conditions
