Relay Hysteresis; Figure 35 Behavior Of Relay That Activates Above Limit, With Hysteresis; Table 11 Relay Wiring: Normally Open (No); Table 12 Relay Wiring: Normally Closed (Nc) - Vaisala Indigo500 Series User Manual

Indigo510, Indigo520 User Guide
Table 11 Relay wiring: Normally open (NO)
Relay activation mode
Relay active above limit
Relay active below limit
Table 12 Relay wiring: Normally closed (NC)
Relay activation mode
Relay active above limit
Relay active below limit
6.5.3 Relay hysteresis
If the measurement you are using to control the relay is likely to move back and forth close to
the activation setpoint, you can set a hysteresis that prevents the relay switching on and off
too frequently.
When hysteresis is used, the relay activates at the defined limit, but does not switch off
immediately when the measurement moves back to the other side of the activation limit.
Instead, with hysteresis, the relay remains active until the measurement crosses the relay
activation/deactivation limit and the additional buffer value.
1
82
Measurement above/below
limit
Above = Relay active
Below = Relay inactive
Above = Relay inactive
Below = Relay active
Measurement above/below
limit
Above = Relay active
Below = Relay inactive
Above = Relay inactive
Below = Relay active
2 3
Relay opened/closed
Closed
Open
Open
Closed
Relay opened/closed
Open
Closed
Closed
Open
Figure 35 Behavior of relay that activates
above limit, with hysteresis
1 Measurement goes above the relay
activation limit (solid line —) and the
relay activates.
2 Measurement falls below the activation
limit, but stays above the hysteresis
limit (dashed line - - -). The relay
remains active.
3 Measurement falls below the hysteresis
limit and the relay switches off.
M212287EN-N