VLC20 - Volume Limiting Controller
| VLC20 - Volume Limiting Controller |
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The VLC20 has been developed to assist ground water users to restrict their daily extraction to the Environment Agency’s ‘no-license’ allowance of 20m³ per day in England & Wales* ( Water Act 2003 ).
The VLC20 control system monitors the volume of water being pumped from the ground and as soon as 20m³ has been reached the borehole pump will be switched off. The pump will then be automatically reactivated at the start of the next 24 hour pumping cycle. If less than 20m³ is raised in any one day, the pump will remain active and the VLC20 will commence monitoring the next period. ( The VLC20 controller requires a volt free pulsed input from a water meter at a rate of 1 pulse per litre. Whilst in ‘active’ mode the pump will be controlled / protected by other, conventional, switchgear : the VLC20 might be mounted within the same enclosure. )
If a requirement of more than 20m³ is anticipated – or as an emergency backup – an alternative water supply change-over can be incorporated in the system. This uses a solenoid valve linked directly to a double pole change over relay within the VLC20 and will change to the alternative supply whenever the pump is turned off. ( This will normally be a mains supply but could be surface water in appropriate circumstances. )
The relay can also be used to operate an alarm to indicate that the 20m³ limit has been reached, that the borehole pump is off and/or the mains water system is active. ( The relay circuit is rated at 250v ac, 8 amps AC1 resistive load and is suitable for switching a relay, or alarm. )
Water volume and time status are held in a non volatile memory which will not be cleared by a power failure : the initial 24 hour timer period will commence as soon as the system is energised but can be reset to cycle from midnight or other convenient time if required.
* In Northern Ireland a 20m³ ‘no-license’ limit also applies but the Environment and Heritage Service must be notified of any abstraction above 10m³. In Scotland a 50m³ ‘no-license’ limit applies but the Scottish Environment Protection Agency must be notified of any abstraction above 10m³.