Relay Deadband (Reset) - Siemens SITRANS L Pointek ULS200 Operating Instructions Manual

5.4.5

Relay deadband (reset)

Deadband (hysteresis) prevents relay chatter due to material level fluctuations at the set
point. These fluctuations are often waves or turbulence on a fluid's surface caused by
agitators in the tank. Once a relay is tripped, the detection level must move beyond the
deadband value before it is reset. The direction in which the deadband is measured depends
on the application of the relay. If the relay is for a high state then the deadband is measured
below the set point. If the relay is for a low state then the deadband is measured above the
set point. Refer to the diagram below. Deadband 1 is used for Relay 1 and Deadband 2 is
used for Relay 2. The deadband value is entered in the units selected, and applies to both
relays and all alarm or control functions except 'Loss Of Echo'.
Factory setting: 0.05 m (0.16 ft)
①
②
③
④
⑤
20
Off
Deadband
On setpoint
Low/low-low alarm
High/high-high alarm
Operating Instructions, 01/2019, A5E32268616-AB
Pointek ULS200