FREQUENCY DETECTION MODULE (FDM) - Frontier Power Products

FREQUENCY DETECTIONMODULE (FDM)GENERAL DESCRIPTIONThe Frequency Detection Module (FDM) is an electronic accessoryfor use with Stamford generators using Permanent MagnetGenerator (PMG) excitation system.Its main uses are in engine control circuits requiring starter motorrelease and overspeed shutdown. Alternatively, the unit can beused for over/under frequency detection.The FDM is powered from the engine battery system and derives aspeed signal from the generator PMG. Voltage free relay contactsare provided for the starter motor release and overspeed functions.TECHNICAL SPECIFICATIONSUPPLY VOLTAGE12 volt version 10-16 V dc24 volt version 20-32 V dcSUPPLY CURRENT12 volt version 200 m A max24 volt version 100 m A maxHz SENSE INPUT All modelsVolts 20-300 V acHz 100 @ 1500 rpmIsolation Optical 2 kVOUTPUTVoltage free contactsIsolation 2 kVRating 5 A @ 30 V dc / 240 dcSETTING RANGELow relay 300-1800 RPMHigh relay 1500-2500 RPMTHERMAL STABILITY0.025% / °CSWITCH OPTIONSMode 0 Low relay ON below set point and OFF aboveHigh relay OFF below set point and ON aboveMode 1Low relay OFF below set point and ON aboveHigh relay OFF below set point and ON aboveUNIT POWER DISSIPATION5 Watts maxPHYSICAL SIZEWEIGHT100 x 75 x 50mm high200 gms maxENVIRONMENTALVibration 20-100 Hz 30mm/s100 Hz-2 kHz 2.0gHUMIDITY0-60°C95% RHOperating Temperature -40 to +70°CStorage Temperature -55 to +80°C

FITTING AND OPERATINGADJUSTMENT OF CONTROLS'HIGH' POTENTIOMETERThe HIGH potentiometer's range is 1500-2500 rpm, it adjuststhe frequency detection point of the overspeed relay(terminals 24, 21, 22). Clockwise increases the frequencydetection point.'LOW' POTENTIOMETERThe LOW potentiometer's range is 300-1800rpm it adjuststhe frequency detection point of the underspeed (or crankingrelease) relay, (terminals 14,11 12). Clockwise increases thefrequency detection point.MODE SWITCHThe mode switch has two active positions which affect theoperation of the low speed (or cranking) relay. Position 0causes the low speed relay to be energised at standstill. Therelay then de-energises when the frequency reaches the setpoint.Position 1 causes the low speed relay to be de-energised atstandstill. The relay then energises when the frequencyreaches the set point.The overspeed relay energises when the speed exceeds theset point and is unaffected by the position of the modeswitch.

BASIC OPERATONThe internal block diagram of the FDM is shown above. Themain functions of the FDM are as follows:-OPTO ISOLATIONProvides isolation between the engine battery system and thegenerator PMG, using opto-electronic technology.SHAPINGFOLLOWER/INVERTERDepending on the setting of the mode switch (0 or 1), thiscircuit either inverts the output of the LOW LEVELDETECTOR or follows it.RELAY DRIVERSProvide the current drive for the relay coils.Converts the speed signal from the PMG into a narrow pulsesuitable for triggering the F - V converter circuit.F-V CONVERTERConverts the narrow pulse from the shaping circuit into aconstant width pulse which is then filtered to produce anaverage DC voltage proportional to speed.LOW LEVEL DETECTORCompares the output from the F-V converter with anadjustable reference voltage, and produces an outputwhenever the F-V converter signal is less than the reference.HIGH LEVEL DETECTORCompares the output from the F-V converter with anadjustable reference voltage, and produces an outputwhenever the F-V converter signal is greater than thereference.

PIN OUT INFORMATION© 2005 Newage International Limited.Reprinted with permission of N.I. only.Printed in England.Barnack Road • Stamford • Lincolnshire • PE9 2NBTel: 00 44 (0)1780 484000 • Fax: 00 44 (0)1780 484100Website: www.newage-avkseg.comTD_FDM_GB_07.05_01