Vaisala Indigo 202 - Setting Relay Activation Limit Using Hysteresis

To
define a single setpoint for relay activation:
1. Open the Settings > Relays menu in the wireless configuration interface.
2.
In the Relays menu, select the relay activation mode from the Output Mode dropdown
menu:
a. select Active above trigger level if you want the relay to activate when the probe
measurement exceeds the set limit
b. select Active below trigger level if you want the relay to activate when the probe
measurement falls below the set limit
3. Select the measurement parameter that is used to control the relay with the Parameter
dropdown.
4. Set the unit of the measurement parameter with the Unit dropdown.
5. Enter the same measurement limit to both the Low Trigger Level and the High Trigger
Level field.
With this configuration, there is no hysteresis. The relay activates or switches o
immediately after passing this point.
6. Select the Err
or State for the relay.
6.3 Setting Relay Activation Limit Using
Hy
steresis
If the measurement you are using to control the relay is likely to move back and forth close
t
o the activation setpoint, you can set a hysteresis that prevents the relay switching on and
o too frequently.
When hysteresis is used, the relay activates at the defined limit, but does not switch o
immediately when the measurement moves back to the other side of the activation limit.
Ins
tead, with hysteresis, the relay remains active until the measurement reaches the defined
tolerated variation limit.
To set a relay activation limit with hysteresis:
1. Open the Settings > Relays menu in the wireless configuration interface.
2. In the Relays menu, select the relay activation mode from the Output Mode dropdown
menu:
a. select Active above trigger level if you want the relay to activate when the probe
measurement exceeds a set limit
b. select Active below trigger level if you want the relay to activate when the probe
measurement falls below a set limit
Chapter 6 – Configuring Relays
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