HELIX GRANVILLE-PHILLIPS Convectron ATM, Instruction Manual

Page: 34 / 98

Chapter 3
26
Convectron
®
ATM Vacuum Gauge Module Instruction Manual
3.3 Setpoint relays
The module includes two single-pole, double throw (SPDT) relays. Each
relay has a programmable setpoint. The setpoint is a voltage level that
corresponds to a specified pressure at which the relay activates and
deactivates. See Table 3-6.
In default mode, relay 1 activates with decreasing vacuum chamber
pressure and deactivates at a higher pressure than the activation pressure,
as illustrated in Figure 3-7.
In default mode, relay 2 activates with increasing differential pressure and
deactivates at a lower pressure than the activation pressure, as illustrated in
Figure 3-8 on page 27. Use internal jumpers to reconfigure relay 2
activation direction. See page 33.
Figure 3-7 Setpoint relay 1 behavior
Table 3-6 Setpoint relay activation direction, range, and hysteresis
Relay Assignment Activation direction Range Hysteresis
Setpoint 1 Vacuum chamber pressure Decreasing pressure 1.0 x 10
–4
to 9.99 x 10
2
Torr 30 mV
Setpoint 2 Differential pressure Increasing pressure –750 to +125 Torr 8 Torr
Deactivate
Activate
Deactivated
Activated
Relay activated
30mV
hysteresis
Time
Vacu
um chamber pressure