GPD Multiplexer for HVAC and Pump Applications The MagneTek GPD Multiplexer System allows one VFD drive to perform the function of several VFDs in multi-motor HVAC and pumping systems. Operation The GPD Multiplexer utilizes one GPD 506 VFD, with horsepower rated for the largest motor, and sequentially controls all the motors to achieve infinitely variable response to system demand. MagneTek has developed the unique and reliable method of transferring motors back and forth between the VFD and the power line as demand increases or decreases. For example, as demand increases, the GPD 506 ramps up a motor until it reaches full speed, at which time the motor is switched to the line to run full speed and the GPD 506 operates the next motor at variable speed. Control of the system is accomplished by the Multiplexer Control Unit (MCU), based upon a single demand input signal (0-10vdc or 4-20mA) from the customer. The MCU has an on-board PID loop for set point control based upon a system output sensor (e.g. flow rate, temperature, pressure, tank level, etc.). The sensor signal is fed to the MCU, which compares it to the customer defined setpoint and corrects system output accordingly. The setpoint can be manually defined on the MCU control console or automatically defined from another control system. Benefits The GPD Multiplexer offers the following benefits: Greatly reduced capital investment Inherent contactor bypass back up for system integrity Lead motor status software that will change the lead motor in the sequence in order to balance wear on the equipment Multiplexer Sequencing Software that automatically substitutes for a failed or offline motor Reduced nonlinear load impact on the power buss (Reduced harmonic distortion) Higher system efficiency since some motors run on the line Soft starting of all motors in the system, reducing peak inrush current and peak demand on the power buss Applications Some of the many uses for the GPD Multiplexer include Chilled Water Systems, Freshwater Pumping Systems, Multicelled Cooling Towers, Compressors, Refrigeration Units, and Irrigation Systems. GPD 506 Design Features Multiplexer System Features Service Conditions Options GPD 506 Features 32-bit microprocessor logic Surface mount devices Carrier frequency: selectable to 15 kHz Keypad operator controls LCD display: English alpha/numeric sixteen character two lines VFD control logic 24 VDC Programmable contacts, one form C and one NO Timer function: contact-initiated RS-232 communications port Volts/hertz ratio: Programmable V/Hz patterns available. Multi-speed settings: 5 available Remote speed reference: 0 to 10 VDC or 4 to 20 mA Setpoint (PID) control with inverse input and Sleep function Signal follower: bias and gain Analog monitor output: 0 to 10 VDC UL, File Number 153436 MTBF: exceeds 28 years Current limited stall prevention Synchronized start into rotating motor via speed search DC bus CHARGE indicator Optically-Isolated controls Phase-to-phase / phase-to-neutral short circuit protection Ground fault protection Electronic motor overload Current and torque limit Fault circuit: overcurrent, overvoltage, and overtemperature Over torque protection Under torque protection Multiplexer System Features Ratings: 5 to 500 HP NEMA Enclosure Main Circuit Breaker with door mounted operator handle Circuit Breaker Branch protection Multiplexer Control Processor Multiplexer Motor Sequencing Software Sequence Compensation for faulted motor Lead Motor Selection Software Analog Follower Software Manual Mode Door Mounted Operators IEC Style contactors UL508 construction Service Conditions Ambient service temperature: -10°C to 40°C (104°F) Humidity: non-condensing to 95% Altitude: to 3300 ft; higher by derating Input voltage: +10%/-15% Input frequency: 50/60 Hz ± 5% Options Current monitor output card PID Mode with Software PID Local/Remote switch Analog Local/Remote switch Auto restart Panel Display/Operator Interface Hi-flow Alarm Software Lo-flow Alarm Software Individual Motor Lockouts Special Motor Sequencing Software Enclosure light Duplex outlet Nema 12 and 3R enclosure --------------------------------------------------------------------------------