inverters are the apple of a cider maker's eye
Making cider relies on a constant supply of water and at Inch's Cider,
part of the Bulmers group, the maker has its own water supply and a novel
way of maintaining accurate pressure in the system. Inch's Cider found
that mains water pressure varied according to the time of year and yet
needed to maintain a steady 6 bar pressure irrespective of demand within
its system. Nick Forrester, Inch's Cider's engineer, devised a system
whereby the standard PID control features of an Hitachi J300 inverter
could be deployed to control the high delivery pump.
steel pumps with 37kW 2-pole motors are fitted within the system to enable
dual redundancy. The pumps, which are switched periodically to share the
duty, are controlled by a fan and pump rated 30kW Hitachi J300 inverter
supplied and commissioned by HID. Pressure sensors located in the pipeline
feed a 4-20mA signal directly to the Hitachi J300 inverter which ramps
up the motor as soon as the pressure starts to fall. To maintain a pressure
above the PID control's set point when demand is low, a simple "donkey"
pump is employed - the pumps do not need to switch in every time a toilet
is flushed! Throughout the commissioning stage, Nick Forrester had a high
level of support from HID's engineering team.