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• If Pegasus2 is repeatedly trying to decrease the output pressure, but not
reaching the target pressure, this is known as a ‘Low unreachable’ condition.
The High unreachable or Low unreachable conditions depend upon a programable
minimum time interval, during which the target pressure has not been achieved.
Only one of these conditions can be set to apply to an installation. When the condition
is triggered, it can be set to activate the S3 latched solenoid (valve).
Normally, the latch solenoid is deactivated, allowing Pegasus2 to provide fine pressure
regulation of the water supply via control of the pilot valve. However, when the latch
solenoid is activated, the Pegasus2 (which must be suitably plumbed into the
installation, and have appropriate settings), can by-pass the pilot valve to get closer to
the target pressure.
Pegasus2 will resume normal control when the output pressure is 2m above the target
pressure (for a High unreachable state) or 2m below the target pressure (for a Low
unreachable state); The S3 solenoid (valve) is once more de-activated.
Information regarding settings are provided within section 4.20.
2.12.4 Theory of operation (Continuous pressure modulation)
The plumbing of a simple Pegasus2 installation is illustrated below:
It uses a “non-latched” model version.
Note: Alternatively, a model that includes a latch solenoid can be used, with the latch
ports not connected, and “No latch” selected in Pegasus2 program settings.
(Refer to the installation examples illustrated in sections 3.2.1, 3.2.2, 3.2.3, 3.2.4)
Note: This illustration uses a standard Pegasus2 plumbing scheme and operation.
It requires the following Pegasus2 settings in IDT:
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