EDM SYSCREW AIR EVO HSE

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SYSCREW 380-1260 AIR EVO HSE
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MODE 2 – ∆P CONTROL [VD]:
VDmodeprovidesvariableowsystem,consistingsolelyoftheprimarycircuitontheuserside.
VDmodeincludesthefollowingcomponents:
• Twopressuretransducersinstalledattheendsoftheheatexchanger(ΔP
EVAPORATOR
) factory installed.
• A dedicated system control, factory installed.
• A bypass valve with actuator supplied loose (installation by the customer).
• Differentialpressuretransducer(ΔP
USER
) supplied loose as accessory (installed by the customer)
Theoptionoffersacompleteandpredenedpackage,guaranteeingsimpleselection,supplyandcommissioning.Inpar-
ticular, the unit includes an additional control system, equipped with an evolved algorithm, which interacts with the main
control of the unit.
VDmodeprovidesfollowingadvantages:
• Implementaninnovativedesign,analternatetotheclassicsystembasedonaprimaryowratecircuitplussecond-
ary circuit.
• An ideal solution for new or completely redesigned systems particularly for comfort applications.
• Acompletevariableowsystemwithmaximumenergysavings.
• Asimpliedusercircuit.
• Itreducesthecapitalcost[CAPEX]oftheuserplantandtheoperatingcost[OPEX].
• The system provides complete and reliable control of the system.
• Abypassvalve,whichensurestheminimumowacrosstheheatexchangerthereforepreventingtheheatexchanger
from freezing.
• The pump speed will reduce automatically to save energy during low occupancy periods.
TheoperatingprincipleofVDsummarizedasfollows:
• The system controller modulates the pump speed based on the condition detected by the user side differential pres-
sure transducer.
• Theusershalldenetherequired∆P
USER
from the chiller controller.
• The pump speed will decrease as the user side shut-off valve closes due to reduction in cooling load.
• Thepumpspeedcanreduceuntilitreachestheminimumallowableowrateontheheatexchangeroftheunit.
• Uponexceedingtheminimumallowableowthreshold,theby-passvalvewillopentriggeredbythefrequencydrive
controller,torecirculatetheowthatisnotrequiredbytheplant,butwhichisnecessarytoguaranteetheowrate
minimum to the exchanger.
• The by-pass valve is controlled by a 4-20 mA input signal and a power supply of 24 V.
• The differential pressure transducer of the user side provided is a 0-10 V signal, which has a PVDF connection. The
transducer must be installed near the terminal of the system that suffers the greatest losses of line load or in any case
in a position where it is possible to detect an adequate pressure value.
FIGURE2:GENERALSCHEMATICSFOR∆PCONTROL