3UG4501 filling level monitoring relay
5.3 Functions
3UG4 / 3RR2 monitoring relays
92
Manual, 05/2016, NEB927043002000/RS-AC/004
Probes for filling level monitoring
To monitor filling levels of electrically conductive liquids, the following probes can be
mounted on the 3UG4501 filling level relays.
●
Three-pole wire electrode
●
Two-pole wire electrode
●
Two-pole bow electrode
●
Single-pole bow electrode for side mounting
●
Single-pole rod electrode for side mounting
These necessary accessories are described in Chapter "Probes for the 3UG4501 monitoring
Note
At the terminals, other resistance sensors in the range 2 to 200
kΩ (e.g.
photoresistor,
temperature sensors, resistor-based position encoders, etc.) can also be connected. The
monitoring relays are therefore also suitable as resistance triggers.
Two-point monitoring
If the liquid level reaches the maximum probe while the minimum probe and reference probe
are immersed, the output relay changes its switching state. The output relay reverts to its
original switching state as soon as the minimum probe is no longer in contact with the liquid.
One-point monitoring
For closed loop control of only one level, the terminals for Min and Max are bridged on the
filling level monitoring relay. The output relay changes its switching state as soon as the
liquid level has been reached. The output relay reverts to its original switching state as soon
as the probe is no longer in contact with the liquid.
Reset response
For reliable resetting, the rated control supply voltage must be interrupted at least for the set
delay time of +0.5 s.
When the rated control supply voltage is interrupted, the output relay returns to the quiescent
state when the power failure backup time has expired (contact 11-12 is closed, contact 11-14
is open). If the rated control supply voltage is switched on again after > 0.5 s + Delay ( t )
(device reset), the output relay switches depending on the set relay switching behavior.
