8200w² Monitor Instruction Manual
2.5 Quick Overview
2.5.1 Fault Indication
Fault indication is via the main display clearly visible on the front panel of the monitor. When there is a
fault present ‘FAULT’ is displayed and fault relay will enter into the alarm condition.
2.5.2 Alarm Activation
With the sensor(s) clear and not in a fault condition ‘OK’ is displayed next to associated sensor. If
however, the sensor is obscured or blocked then the specific sensor relay will enter into the alarm
condition and ‘ALARM’ will be displayed next to associated sensor.
2.5.3 Delay Operation
A delay can be introduced between conditions for an alarm turning on being met and the relay
changing state. At any time during the selected delay, if the conditions for turning the alarm on are
removed, then the delay will end and the alarm relay will not change state. Similarly a second delay
can be introduced between conditions when an alarm turning off and the relay changing state.
These delays can be set between 1 & 90 seconds. The delay functions are in place to try to avoid the
occurrence of false alarms that may be caused by suspended debris or conversely the clearing of
alarms prematurely.
2.5.4 Alarm Relays
The alarm relays are internally configured for fail safe operation. When power is applied and the
sensors are clear the relays will be energised, on alarm the relays are de-energised. Each alarm has
normally closed and normally open contacts for external signalling, the normal condition is when the
unit is powered and the alarm is off. There are two alarm relays each assigned to a sensor.
2.5.5 Fault Relay
The fault relay is activated in two instances: when there is a problem with a sensor or due to a failure
in the power supply to the system. In the latter case, this will cause the relay to be de-energised,
resulting in a fault state. The fault relay is common to both channels on the 8200w² and will be
activated if one of the sensors fails or is removed. A sensor fault could be as simple as the sensor
connector is unplugged or wire broken and the monitor can no longer communicate with the sensor.
The relay can be wired as normally closed or normally open on the output side depending on customer
preference.
2.6 Applications
The 8200w² Monitor, when combined with a compatible sensor, is designed for use as a sludge
blanket level detector, a sludge density switch, or as a suspended solids/turbidity switch. The 8200w²
Monitor is therefore suitable for interfacing with automatic de-sludging control of primary and
secondary settlement tanks, thickener control through high and low blanket level alarm, or as a simple
alarm in a water/ waste water flow.
2.6.1 Sludge Blanket Level Detection
When used for this operation the monitor uses an SoliTechw² IR series sensor, which is suspended by
its cable to the desired monitoring depth in the tank. When the settled sludge reaches the sensor then
the alarm output is activated. This can then be used as an input to a process system to directly control
pumps, bell mouths or simply to alert the operator. The same principle can be used to monitor when
the sludge reaches a minimum point when it is being removed from the holding tank.
229844IM Issue 01 Issue Date 24/06/2019 ` Page 7 of 34
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