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3. System overview
3.1 Function
The product can be configured to control the level of a boiler, tank or vessel, by operating a
pump, valve or solenoid. Typical applications:-
On / off control:
-
Pump control.
-
Two alarm outputs.
-
4 - 20 mA level retransmission output (isolated).
Note: A solenoid valve may be used instead of a pump.
Modulating control:
Modulating valve control using a valve motor drive or 4 - 20 mA control signals.
-
Two alarm outputs.
-
4 - 20 mA level retransmission output (isolated).
Note: The 4 - 20 mA level output is only available when the product is configured for
valve motor drive systems.
3.2 Inputs
The product has two inputs to accept the following signals:
-
Level probe or transmitter 1 - 6 V or 4 - 20 mA.
Note: The level probe must be long enough to sense over the complete level range.
-
A 1 K potentiometer input ~ for Valve Motor Drive (VMD).
3.3 Outputs
The output control signal can be configured / wired to work with a pump or a modulating
control valve. It also provides relay outputs for high or low level alarms and can provide an
isolated 4 - 20 mA retransmission output.
3.4 Other features
An additional filter can be selected to increase the damping effect for turbulent conditions.
To prevent unwanted or inadvertent changes being made, all commissioning parameters are
protected with a pass code.
The product can communicate via an infrared link between adjacent boiler house controllers
(Spirax Sarco products only). It is designated as a slave unit only - see Section 7 -
Communications.
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