Hycontrol Ltd V1.5
Page 7
4.2) Cabling and Connections
The easiest way to connect the sensor is to use a 4-core screened cable. The cable does
not need to be screened for shielding purposes but the screen is a convenient way to
connect the earth return if the set-up in figure 3 or 4 is used. If the sensor is fitted to a metal
tank with the fitting connected to the tank as shown in figure 2 then the screen is not
required.
The sensor output has volt-free contacts which open when foam is detected. This can be
used to switch 24V dc to a PLC or a pump. Some PLC inputs can be wired directly to volt-
free contacts and can detect the contact closure. The output contacts are provided by an
isolated solid state switch. The maximum load is 500mA. If switching inductive loads then a
suppressor or snubber should be fitted to protect the output contacts.
The power supply required is 24V dc. The maximum current required is less than 100mA so
the cable rating is not critical. See figure 1 for connections.
Return via
probe fitting
metal ground
electrode
Plastic Tank
Figure 5 – Plastic Tank
With return path via
ground electrode and
fitting.
