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Hawker Electronics - P4 Plug in Level Controller for Panel Mounting
Control Between Two Levels or High or Low Alarm with a Single Unit Controller
Suitable for a wide range of Conductive liquids e.g. Sewage, Water, Acids, Alkalis, Milk, Beverages, Paper Stock, Detergents, Wine etc.
Precise level detection with no deadband.
Protection against dry running.
Prevents pump overrun resulting in reduced operating costs.
Ignores electrode fouling.
Simple 'Low Cost' installation.
Wide selection of electrodes and mounting accessories.
Intrinsically Safe option (P7/IS).
Principle of Operation - Relies on the conducting properties of liquids to
complete an electrical circuit between an
electrode and the metal tank. For non-metal or
coated tanks, the path may be through
pump pipework. Alternatively, an earth
electrode extending below the lowest active
electrode may be fitted. Level sensing
electrodes are normally mounted vertically and
the controller switching action occurs as the
liquid touches or leaves the electrode. Pressure
tight electrodes are available for side entry if
required. A low voltage A.C. signal is used on
the electrodes to prevent electrolysis.
Sensitivity - The input switching point is adjustable between
100 & approx 18,000 ohms, which suits most
applications, Higher values up to 500,000 ohms
are also available for high purity water.
Switching Differential - Better than 5% of set sensitivity i.e. 50 ohms at
1000 ohms (5 ohms at 100 ohms sensitivity).
This is necessary to avoid relay hold-on at the
lower electrode caused by material clinging to the probe, electrode wetting, and viscous
liquids such as sludge. This close switching
differential also allows the high electrodes to
ignore foam layers. (Fixed sensitivity
controllers without a close switching differential
are only suitable for clean water applications).
Fail Safe Feature - Set by a switch on the front panel. The control
relay will revert to the alarm condition in the
event of a power failure. L.E.D. status
indication is provided. As a general rule
emptying applications require a fail safe low
(FSL) setting and filling applications a fail safe
high (FSH) setting.
Mounting Details - The plug-in controller is designed for mounting
into an international 11 pin DIN rail/surface
mounting socket enabling ease of installation
and servicing. The base of the plug-in
enclosure has two plastic clips which enable
the P4 unit to be securely locked into the
Hawker supplied 11-pin base. (The P4 will
however fit other bases but the clips may not
Please note - Product designs and specifications are subject to change without notice. The user is responsible for determining the suitability of this product.
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