2 HVAC & WATERHVACHeating, Ventilation and Air-Conditioning (HVAC) is all about efficiency:Room temperatures need to be maintained at optimum levels to achieve the best occupant confort.It is essential to consider how hit targets in reducing costs and carbon dioxide (CO2) levels.
3 HVAC & WATERWATER - PUMPAn operating pump will normally consume more power than the hydraulic circuit requires and it is usually positioned in unconfortable site:It is essential to consider how achieve targets in reducing power consumption, costs and CO2 levels.Maintenance time and costs need to be reduced in order to avoid long plant standstill.Pumps are used in many applications. They are commonly used for water supply, water treatment and pressure boosting in buildings, also for cooling water and general service water industry.E.g.:- Fire fightingIrrigationPumping from shallow boreholes (using an ejector)Small pumps can be used for fountains or swimming poolsIn Italia**Le pompe e i ventilatori sotto i 90 kW sono oltre 2 milioni di cui oggi solo l’8% regolati da inverterGli inverter sono tecnicamente ed economicamente applicabili ad almeno un ulteriore 52%** Studi Save “ VSDs for Electric Motor system” e “ Improving the penetraetion of EEM and Drives”
4 Most of the time they have excess capacity HVAC & WATER - Why VFD flow control?HVAC & WATER systems are designed to operate under the most extreme conditions and, HVAC typically, in the “worst case” situations that the system will encounterMost of the time they have excess capacity
5 Problems of traditional flow control HVAC & WATER - Why VFD flow control?Problems of traditional flow controlLow system efficiencyDifficult in regulationElectromechanical stressNoise due to mechanical resonanceHigh starting currentBig supply cable section or cable numberMaintenance cost and time
6 HVAC & WATER - Why VFD flow control? Reducing the capacity of the systems when full capacity is not required provides significant energy savings without sacrificing system performanceVFD Flow control
7 Secondary Hot/Chilled Water Pumps HVAC & WATERReturn FanSupply FanPrimary cold/ChilledWater PumpsCondensorWater PumpCooling Tower FansSecondary Hot/Chilled Water PumpsThe variable torque applications shown here can provide significant energy savings when they are controlled by adjustable frequency drives.
8 Pump Curve Operating Point System Curve HVAC & WATER - Characteristic Details of the way that drives are interfaced with the building’s HVAC system have a major impact on the amount of energy that can be saved. In some cases, the simple relocation of a sensor or the changing of a setpoint can be critical to achieving maximum energy savings. This portion of the presentation considers factors that are critical to maximizing energy savings. While this example deals specifically with a pumping system, the same concepts apply to fan systems.The Pump Curve determines the relationship between the flow and pressure that the pump can produce. The Control Curve determines the same relationship for the controlled system. Where these two curves intersect determines the pressure and flow that will result.Q is proportional to the pump rotational speedH is proportional to the square speedPower is proportional to the cubic speed
9 P Power Flow x Pressure WASTED Power New Power required Pressure HVAC & WATER - Traditional throttling flow controlPNew PowerrequiredWASTED PowerPressuredropPowerFlowxPressurePowerto loadIt helps to be able to visualize the amount of power that is associated with any particular combination of pressure and flow. Since power is proportional to the product of pressure and flow, the area of the rectangle that is formed between the axes of the pressure-flow graph and the operating point represents the power that is associated with the flow.It should be noted here that this describes the power associated with the flow from the pump. It does not take into account the inefficiency of the pump, the motor, or any other portion of the system. While consideration of these inefficiencies will be important for a precise analysis of the total power requirements of the system, these do not need to be considered for this discussion.Since the system will seldom need to operate at its full design flow, it is important to consider how to reduce the flow to the level that will be required under less severe conditions.The traditional method of reducing the flow from a pump is to close a throttling valve. This increases the pressure that the pump needs to produce. The operating point is said to “ride up” the Pump Curve.An examination of this situation shows that the power associated with this flow, as shown by the area of the purple rectangle, has decreased. However, only the bottom portion of this rectangle represents the flow and pressure delivered to the load. The rest of the rectangle represents power that is lost through the pressure drop across the partially-closed valve.
10 VFD avoids the pressure drop by controlling the speed of the pump HVAC & WATER - VFD flow controlCoolingCoilPrimaryChilled WaterPumpSecondaryChill WaterDifferentialPressureSensorChilledWaterPump DriveChillerAirDuctAn adjustable frequency drive avoids this large pressure drop by controlling the speed of the pump. While there are a number of different ways of accomplishing this, the simplest and most common is to measure the differential pressure across the most distant significant load. A setpoint controller is used to adjust the speed of the drive to maintain the required system differential pressure. The concept here is that, if the required pressure is maintained here, sufficient pressure will be available throughout the system.As the valves in the system are closed due to a reduced demand for flow, the pressure in the system will tend to increase. The differential pressure sensor will indicate this and the setpoint controller will slow down the drive to maintain the desired pressure.The opposite happens when the demand increases.VFD avoids the pressure dropby controlling the speedof the pump
11 P «Throttle control» Power required «VFD c.» Power required HVAC & WATER - VFD flow control«Throttlecontrol» Powerrequired«VFD c.» PowerrequiredInstead of following the Pump Curve for a fixed speed, the operation of the system follows the Control Curve. As the required flow decreases, both the pressure and the flow decrease. As a result, the reduction in power is significant.If the setpoint pressure was zero, the pressure would be proportional to the square of the flow. As a result, since power is proportional to pressure times flow, the power would be proportional to flow cubed. This is the familiar centrifugal fan or pump affinity law. When projecting the energy savings possible by using an adjustable frequency drive, it is important to remember that this only applies when the setpoint pressure for the Control Curve is zero. It is also important to remember to consider the efficiencies of the various devices in the system.P
12 Proportional Integral Derivative function (PID) HVAC & WATER - VFD flow controlProportional Integral Derivative function (PID)The sum of these three actions is used to adjust the process via a control element such as the position of a control valve or the power supply of a heating element.PID controllers attempts to correct the error between a measured process variable and a desired set-point by calculation and then outputting a corrective action that can adjust the process accordingly.
13 HVAC & WATER - VFD flow control The target value or Set-point has to be set by user. This could be the desired pressure, flow, temperature, vacuum, etc.E.g.: this reference is the measure of how much fluid is required to be sent to the wastewater pipeline.Feedback valueSet pointMotor & PumpVSDTransducerPump outletControllerDetectorFeedback valueControlled VariableActuating SignalMotor freq.ComparatorΣSystemSet point0-10VDC or 4-20mA signal
14 High degree of protection against dust and water sprays HVAC & WATER - VFD flow controlThe standard «ready-to-install» IP54 SINUS PENTA solution is particularly suited to HVAC & WATER applications:High degree of protection against dust and water spraysAbility to mount without additional enclosures and ventilationPID functions for automatic controlBuilt-in EMC filterOnboard communications allows control and monitoring
15 Extensive I/O with internal comparator functions HVAC & WATER - VFD flow controlThe standard «ready-to-install» IP54 SINUS PENTA solution is particularly suited to HVAC & WATER applications:Extensive I/O with internal comparator functionsFire Mode function for extended operation in critical periodsSpeed Search function to start on a rotating loadReal Time Clock (RTC) function to adjust confort to demands that change over the weekMultipump functionRobustness and reliability
16 HVAC - SINUS PENTA advantages AIR HANDLERReduce energy costs and CO2 emissions Variable torque load characteristics use less energy as speed is reducedReduce supply demand Drives reduce motor starting current up to 10 timesReduce noise in buildings Airflow noise decreases by eliminating starts/stops and optimising flow ratesReduce shock and vibration Drive avoids running at speed near system resonant frequency and provides controlled accelerationIncreased life of motor belts Drives provide low torque starts reducing stress on belts, pulleys and keys
17 WATER CONDENSER CHILLER HVAC - SINUS PENTA advantagesWATER CONDENSER CHILLERReduce energy consumption Provide improved efficiency and reduce energy requirementsReduce CO2 emissions Due to the energy savingsProvide continuous operation Restart a spinning motor after momentary power loss
18 Reduce CO2 emissions Due to the reduce energy consumption HVAC - SINUS PENTA advantagesCOOLING TOWER FANEnergy savings and reduce energy costs Motor use less energy as speed is reducedReduce CO2 emissions Due to the reduce energy consumptionReduce maintenance requirements and reduce operating costs Robust constructions and energy efficient
19 Wide power range for different pump sizes WATER - SINUS PENTA advantagesPUMPReduce energy costs and CO2 emissions Variable torque load characteristics use less energy as speed is reducedReduce demand charges Drives reduce motor starting current up to 10 timesControl of pressure of flow using PID The drive can optimize the pressure flow, and its linearity variations, with a single pressure transducerWide power range for different pump sizesNetwork communications Support all major protocolsPrevention of water hammer, pipe stress, valve, pump seals and cavitation Extends the life of the entire system
20 WATER - MULTIPUMP application overview Controls a multi-pump pumping system (up to 5 pumps)One pump is the speed-controlled master and the other pumps are variable speed or fixed speed slavesMulti-Master modeConnection using I/O or ModbusAutomatic balancing of operating hours of all pump setsElimination of water hammer
21 WATER - MULTIPUMP: Fixed Speed Slaves (FSS) The Master pump operates to ensure the system fine-tuning. The slave pumps are started up/stopped based on the criteria below:Percentage of the working power required for the master pump (allowing optimum performance of the plant).Maximum allowable adjusting error.Maximum difference among the working time of each available pump.The power ratio of the connected pumps must meet one of the following requirements:All pumps must have the same power ratings.The connected pumps can have different power ratings, provided that each pump with the greatest power rating is matched with lower-rated pumps that, if combined, have power ratings equal to or higher than the former pump.The power rating of the master pump must be higher than/equal to the power rating of the lower-rated pump.
22 PENTA MULTIPUMP SOFTWARE WATER - MULTIPUMP: Fixed Speed Slaves (FSS)PENTA MULTIPUMP SOFTWARESoft-Starter ASABBasic diagram for a fixed-speed plant including 4 slave devices and 1 MP Penta drive controlling the system in analog mode.
26 WATER - MULTIPUMP: Variable Speed Slaves (VSS) The slave pumps and the master pump are started/stopped based on the following criteria:Percentage of the working power required for the master pump (allowing optimum performance of the plant).Maximum allowable adjusting error.Maximum difference among the working time of each available pump.All the connected pumps must have the same power ratings.
27 PENTA MULTIPUMP SOFTWARE WATER - MULTIPUMP: Variable Speed Slaves (VSS)PENTA MULTIPUMP SOFTWAREModbus MASTERMODBUS RTUModbus SLAVEMULTIMASTERFUNCTIONPENTA DRIVEPENTA DRIVEThe diagram above shows a configuration for a variable-speed multipump system, serial communications and Multimaster function.