Refrigeration, air-conditioning and cooling technology - 2007.pdf
Refrigeration, air-conditioning and cooling technology - 2007.pdf
Refrigeration, air-conditioning and cooling technology - 2007.pdf
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
PLH_KKK_32_85.QXP 25.05.2007 10:10 Uhr Seite 35PUMP PERFORMANCE CONTROL∆p-T control modeIn the ∆p-T control mode (programmable onlywith the IR-Monitor) the electronics circuitryvaries the setpoint differential pressure value tobe maintained by the pump as a function of themeasured fluid temperature. This temperatureprompteddifferential-pressure control modecan be used in constant-volume (e.g. one-pipesystems) <strong>and</strong> variable-flow systems with varyingfeed temperature. Conversely, the ∆p-T controlmode supports heating pump <strong>technology</strong>, providedthe pump is installed in the return pipe ofthe system.Delivery head H [m]∆p-T controlH maxpos. operationneg. operationH minT max T medH var.T minQ minQ maxFlow Q [m³/h]DDC operating modeIn this mode the actual/setpoint level assessmentrequired for control is referred to a remotecontroller. An analogue signal (0...10 V) is fed asa manipulated variable from the external controllerto the Wilo pumps with built-in electroniccircuitry. The current speed is shown on the display,<strong>and</strong> manual operation of the pump is deactivated.DDC pump operating mode with built-inelectronic circuitryDDC operation always means that a signal fromthe higher-ordered controller must be registeredby the Wilo products. In addition, floating contactsfor switching on-/off, etc. are required,depending on the used product. Also, floatingsignals or 0...10 V (0/4-20 mA) signals can beused by the Wilo products for monitoring <strong>and</strong>logging. Details can be found in the productcatalogues.DDC operating mode with Wilo switchgearn [1/min]n maxSetpoint100%n minOff1 1.5 3 10U [V]When a Wilo control device is used, the setpointdepends on the used signal transmitter. Whenthe signal transmitter DDG 40 is used, this means,for example, that the setpoint at 0 % is equal tozero meters <strong>and</strong> at 100 % is equal to 40 meters.Analogously, this applies for all other measuringranges.0%0/2 V0/4 mA10 V20 mASignal inputWilo Planning Guide - <strong>Refrigeration</strong>, <strong>air</strong>-<strong>conditioning</strong> <strong>and</strong> <strong>cooling</strong> <strong>technology</strong> 02/2007 35
Change language