Manual KW903 SP Iss 04

8/20/2019 Manual KW903 SP Iss 04

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KW903-SP

SYNCHRO RETRANSMISSION UNIT

AMI MARINE (UK) LTD


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AMI Manual KW 903-SP Doc No: AMI TM903-SPIssue: 4

CLASSIFICATION: Commercial In Confidence

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This Page Left Blank Intentionally



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DocumentIssue

Date Modification Number (where applicable)Brief Record of Change and Reason for Change

1 15.08.02 Original Issue2 14.10.05 Update of company contact details3 15.11.07 Update of Address4 16.05.08 Change of address

NOTE: All alterations must be verified by re-authorisation and approval of thecomplete document.



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SYNCHRO RETRANSMISSION UNIT

KW903-SP

TECHNICAL MANUAL

CONTENTS

INTRODUCTION........................................................................................................ 7 SPECIFICATION........................................................................................................ 7

MAIN TRANSFORMER.............................................................................................. 8 ANSCHUTZ ADAPTER .............................................................................................. 9

PRE - INSTALLATION CHECKS.............................................................................. 10 INSTALLATION NOTES........................................................................................... 10 TESTING THE REPEATERS ................................................................................... 12 TESTING THE GYRO .............................................................................................. 13 OPERATIONAL CHECKS ........................................................................................ 14

CHANGING BETWEEN No 1 to No 2 input.............................................................. 15 PRINCIPLES OF OPERATION ................................................................................ 16 MEASURING PHASE SHIFT ON OUTPUT ............................................................. 18 FINAL TEST PROCEDURE ..................................................................................... 19

TRANSFORMER SETUP......................................................................................... 20

BOARD LAYOUT ..................................................................................................... 21

AMI MARINE (UK) LTD

Unit 2Tower LaneEastleighHampshireSO50 6NZUnited Kingdom

Tel No: +44 (0) 23 8048 0450Fax No: +44 (0) 23 8065 1126

Email: [email protected]

Web: www.amimarine.net



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SYNCHRO RETRANSMISSION UNIT KW903-SP

INTRODUCTION

The RTU converts several types of gyro compass output to 360:1 synchro signals themain application being in refits on ships that already have synchro repeaters.

Input signals may be stepper including Sperry a/c stepper NMEA 0183 or 1:1synchro. A second NMEA input provides for back up from a magnetic system orsecond gyro.

The unit is all solid-state built for highest reliability and simplicity of installation. The

KW903 features test modes to prove a system installation. The synchro output isgenerated “digitally” without high power amplifiers. The software makes the synchrooutput move in small steps 24 per degree and thus a smooth rotation is given evenfor a coarse input of 6 steps per degree.

SPECIFICATION

INPUT: - Standard Version: Standard DC stepper 4 to 35 v DC pure DC orRectified unsmoothed DC or “90 x 400Hz contactlesstransmitter. Tracking rate > 200 degrees/sec.

OR NMEA 0183 $HEHDT xxx.xT cr If:

INPUT: - 1:1 Synchro Version: 115/90 or 26/11.8 synchro 50/400 HzResolution 12 bits .09 degree.OR NMEA 0183 $HEHDT xxx.x T cr If.

SECOND INPUT: NMEA 0183 all valid heading sentences.First or second input selectable by switch.

SYNCHRO OUTPUT:Voltage set by transformer used.Standard voltages are REF/Signals 115/90 50/68 60/24Ref. current 2A. Phase current max 0.2A per phase.(Subject to test and tuning of reactance).1 revolution per degree follow up rate adjustable 2 to 11deg/sec.24 states per revolution with software control.

NMEA 0183 OUTPUT: Diagnostic data.



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MAIN TRANSFORMER

The transformer is multi tapped as best shown in the schematic showing variousconnections. The standard transformer gives a 115v ref. 90v signals output but thisis normally REDUCED by selecting the 132v mains input tapping. This runs thesynchro repeaters at a reduced voltage and we have found that under-rating isbeneficial. The exact voltage applied is not critical and you will be checking that therepeaters follow later.

The output can be fine-tuned with the addition of another transformer. Anschutzrepeaters use 50v/20v or 60v/24v. We have an adapter for those voltages. Seebelow.

The KW903’s reference output is intended to drive synchros, not high power courserecorders etc. If the ship’s equipment draws high power from the reference supply fitan external reference transformer and disconnect the KW903’s reference supply.You may find such an external transformer already exists in the old system such asKurs and may be reused.

If the standard transformers do not produce exactly what is required we can maketransformers to suit your exact need.

DO NOT CONNECT SYNCHROS UNTIL YOU HAVE CHECKED THE KW903OUTPUT!



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9

ANSCHUTZ ADAPTER

R

BK

Y

O

BL

GY

V

BN

R

BK

Y

O

BL

GY

V

BN

R1

R2

S1

S2

S3

R1

R2

S1

S2

S3

INPUTFROM KW 903

OUTPUTTO REPEATERS

12 WAY TERMINAL BLOCK

NOTE IT CAN BE REMOVEDFROM THE PCB TO EASE

ASSEMBLY

KW 903 LOW VOLTAGE ADAPTERBOX CONNECTS BETWEEN RTU

AND REPEATERS

THE UNIT TRANSFORMS THESTANDARD SYNCHRO VOLTAGEDOWN TO A NOMINAL 24 VOLTSFOR ANSHUTZ

THE KW903 REFERENCE IS SETFOR NOMINAL 50 VOLTS OUT

ENCLOSURE IS 155 x 220 x 55 mmDIECAST ALUMINIUM BOX



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PRE - INSTALLATION CHECKS

When a gyro is being replaced because it is old and worn out our experience showsthat there will also be repeaters old and worn out. This includes electrical andmechanical faults. The gears of the repeaters should be checked for wearparticularly the small gear on the synchro motor. It is essential faulty repeaters aredisconnected or repaired. Just one faulty synchro repeater can stop the wholesystem working.

Use the existing gyro before it is switched off turn it and check that all repeatersfollow. We provide a checklist to record your tests.

Disconnect the synchro transmitter and measure the resistance of all the repeaters inthe system connected in parallel.

R1 - R2 = ohms

S1 - S2 = S2 - S3 = S3 - S1= These values should be equal

R1 - S1 = Should be open circuit

R1 - Ground = Should be open circuit

S1 - Ground = Should be open circuit

INSTALLATION NOTES

POWER

Measure power supply input. If the voltage varies from 110/220 the synchro outputwill vary in the same ratio. The KW903 transformer has taps, which may be used toadjust the output voltage.



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GYRO INPUT

If the gyro has an NMEA 0183 output connect it to NMEA channel 2. This will beselected as “No. 1”. NMEA data to 0.1 deg provides a smoother output thanstepper.

Connect stepper input to SK5. For DC input set jumpers J1, J2, J3 to full waverectification. This handles either polarity and rectified unsmoothed DC.

For 90x 400 Hz contactless transmission set the three jumpers for half waverectification.

Set J4 and J5 to suit the gyro input. These jumpers indicate the gyro type at switch-

on and have no effect if changed after switch-on.

For NMEA heading input instead of stepper the jumpers do not matter.

90x contactless transmitter as in SR220 It’s Reference R1, R2 is supplied with 115v 400Hz.

Do not connect its R1, R2 to KW903!Connect transmitter “N” to KW903 stepper commonConnect S1, S2, S3 to S1, S2, S3Jumpers J1, J2, J3 to half wave rectified.

If KW903 output turns wrong way final test reverse S1, S2.

Note stepper input LEDs may not go out entirely. This is ok for 90x NOT ok for DCstepper!

SECOND GYRO OR MAGNETIC BACK UP

Connect the NMEA input to NMEA Channel 1. It will be selected as “No2”. Thischannel is programmed to use all valid heading inputs, including Cetrek proprietarydata. (Channel 2 only accepts gyro $HEHDT).



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TESTING THE REPEATERS

DISCONNECT SYNCHRO OUTPUT

SET SWITCH TO “ B” SWITCH ON!

TEST FACILITY

The KW903 - SP starts in a test mode. Changing the switch exercises the outputeven without a gyro connected. This facility is used to test the synchro repeaters.Try the positions and you will see the synchro output LEDs rotate.

A = Anticlockwise rotation at 1 degree/second.

B = Stop. (Belay)

C = Clockwise rotation at 1 deg/sec.

D = Demo mode very slow at 0.1 deg/sec.

E = Demo mode at 1 deg/sec.

F = Fast demo mode 4 deg/sec.

TESTING THE SYNCHRO REPEATERS

In the synchro distribution unit disconnect all repeaters. Connect to the KW903.Switch to B and switch on the KW903. The advice which follows will let you test thesynchro repeaters as best you can, and find possible faulty ones.

There are 1 ohm resistors in the reference and phase outputs. Connect a meter setto a low voltage range across these resistors to measure reference and phasecurrent. The KW903 can supply 2A reference and 2A current in any one phase. (1vmeasured = 1 amp of course). Ideally please connect an oscilloscope.

Connect up the synchro repeaters one by one and make sure they do not take

excessive current.

To test that the repeater turns and follows correctly switch from B to A or C. Since itwill be rotating at 1 deg/sec and the NMEA out led is flashing at 1 per second youcan have a good idea how far you have turned. It is helpful to have two people withportable radios during these tests. If any repeater draws unusual current or does notturn smoothly or loses step it is faulty. Isolate it and do not connect until it is fixed.

Finally set to B and align all the repeaters to the same heading. Switch to D andleave the KW903 exercising all the repeaters. At any time you can stop it byswitching back to B. All repeaters should still be aligned. Next try the faster testmodes E and F. if any drop out of alignment remove them they are faulty.



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FINAL MEASUREMENT

When all is satisfactory stop the rotation by selecting B but stop it if possible at aposition where the phase you are measuring is taking maximum current. Switchingfrom B to A and back quickly will nudge it into place. Complete the checklist with thisvalue. If you have an oscilloscope also measure the phase shift: (see note.)

TESTING THE GYRO

Switch off. Set the hex switch to 0 and switch on. Toggle the alarm switch and leaveit on. If the alarm sounds the KW903 is indicating a GYRO FAULT!

The stepper input LEDs will be seen to rotate if the gyro turns. NMEA input LEDs will

flash in time with the data input. Align the repeaters to the gyro. Turn and hold thegyro and check the repeaters move to that position. Swap a pair of wires if it turnsthe wrong way.

If the alarm sounds on rapid turns of the gyro it is usually caused by the stepper RTUbeing too lightly loaded, so that its internal capacitance cause slow transitions andfalse steps. Fit load resistors across the stepper output e.g. 100 ohms.

OUTPUT FOLLOW-UP RATE

The hex switch allows selection of output rotation rate according to the formula

Degrees per second = 2 + Switch setting. Thus 0 = 2 deg/sec 3 = 5 deg/sec. Fasterfollow up rates are available up to 9 but are not recommended. Chose a setting onestep faster than the ship can possible turn.

This feature is provided because repeaters may not follow really fast turns, which agyro may give in “slew” mode. Do not confuse this follow-up with input tracking rate.The KW903 tracks DC stepper at more than 1000 degrees per second but it limits theoutput rotation for the sake of the synchro repeaters.



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EXTERNAL ALARM

For safety reasons an independent external alarm should be connected. TheKW903 provides a pair of contact that are held open when all is well. There are alarge range of alarms easily available. We recommend an audible alarm with speechoutput e.g. RS 216-3894.

Such an alarm can not detect faults on the synchro transmission system, which couldbe caused by a KW903, output failure or a faulty synchro repeater, shorts, etc. Thisis so with all transmission systems. To detect such faults a synchro monitor and off-course alarm should be fitted. The AMI KW950 is recommended.

OPERATIONAL CHECKS

STATUS LEDGreen = all ok

Flashing = a problem detected e.g. gyro false steps, gyroor power interruption, loss of reference in output.Toggle alarm switch to clear alarm condition.If alarm returns there Is a problem

Red = Alarm is switched off, or KW903 hardware failure.The software does not generate red state.

Off = No 5 volt power!

STEPPER INPUTThe LEDs indicate state of gyro input and rotate insequence i.e. 001 011 010 110 100 101. LEDs all on or alloff indicates a gyro problem.

NMEA 0183 INPUTSThese LEDs flash in time with the data input.

NMEA 0183 OUTPUTFlashes at least once per second with each data output itflashes at a faster rate when the ship turns.

SYNCHRO OUTPUT LEDSThese indicate roughly the state of the synchro output.The brightness changes but they only go out at exact halfdegree positions.



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CHANGING BETWEEN No 1 to No 2 input

Put a man on the wheel and check your course with magnetic compass. Changeover the selector switch. The KW903-S will maintain the last synchro output stateuntil a new changed heading comes in. When you see the output is happily followingthe input with no alarm condition the job is done.

If your two inputs were different for instance gyro saying 010 and second input from amagnetic compass saying 020 you may have expected to change the mechanicalrepeaters 10 degrees on switch over. This does not happen there is a smoothtransition from one to the other.

Check your heading and alignment of repeaters and always navigate with caution.

Magnetic p ick-off and fluxgate compasses

When used to back-up a gyro, results are often disappointing. It is a very skilled taskto make a pick-off coil system work well. Electronic fluxgate compasses need to beadjusted or compensated like a magnetic compass and experience has shown it verydifficult to make them work on steel ships.

The KW903 needs an NMEA input from such sensors. Fit an NMEA headingindicator to indicate the magnetic heading then you will see just how it is performing.

The KW903 will perform as well as it’s input.

Some electronic sensors output heading in 1 degree steps so the KW903 will beseen to rotate to whole degree positions.

A properly installed and corrected magnetic system will work well.



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PRINCIPLES OF OPERATION

The heart of the unit is the microprocessor software in EPROM, which controls thewhole input and output processing. The unit divides into convenient sections.

1 Power supply

2 Gyro input interfaces

3 Synchro power driver

4 Microprocessor

Power supply

The mains A.C. input is fused switched and filtered. The filter capacitors are centretapped to earth and must be earthed for safety. The filtering is for EMC reasons.

The multi-tapped transformer is specified to provide secondary voltages for referenceand synchro phases. One “9v” winding is used for the 5v logic power supply.

Gyro input interfaces

Stepper gyro signals including A.C. Sperry signals are fed to opto isolators. Theiroutput goes to ports on the microprocessor. It is entirely up to the software to

process these signals to keep track of turns. Stepper signals give 6 steps perdegree.

The software will cause the “alarm” condition if a false step state is ever found thatbeing a gyro fault. The most common reason is the gyro’s step signals moving slowlydue to capacitance when the stepper output is lightly loaded. Fit some load resistorsto cure it.

The 1:1 synchro interface uses a synchro to digital converter with data transfer viaopto isolators to the microprocessor. Thus the common line of the SDC interfacefloats above ground for we do not want to put any ground on the synchro transmitter.

The software is responsible for reading and turning the SDC data into heading. TheSDC chip has a fault indication bit which is active if there is a problem with thesynchro input. Again this causes the alarm state. The 12 bit accuracy gives headingto better than 0.1 degree. The chip is a high precision device. The synchro inputmust be phased and adjusted to achieve precise NMEA output.

NMEA 0183 inputs are also opto isolated before being passed to the microprocessorwhich has 2 UARTS to receive the data. The software is written to accept all validNMEA sentences from the No 2 Ch 1 input and the standard gyro sentence $HEHDTon the No 1 Ch 2 input.It is again the software, which controls the use of No1 or No2 inputs.



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Synchro Power Driver

A synchro transmission has three values at 120 degree offsets whose value is V*sine of angle. Thus the voltage say S1-S2 varies from 0 to 90v at 90 degrees 0 at180 degrees and reverse phased 90v at 270 degrees. The standard synchroretransmission system is 1 revolution = 1 degree.

Since input signals are only accurate to 0.1 degrees the synchro output can onlyreflect this that is 10 steps per degree 36 degree turn of the motor. Stepper inputmeans rotation positions at 60 degree intervals. This design provides 24 positions ofthe output at 15 degree intervals. The software moves the synchro through these 24positions to smooth the jumps in heading output.

The principle behind the design is that we will generate just two outputs S1-S2 andS2-S3. The value of S3-S1 comes automatically and I invite you to work it out foryourself.

To achieve 24 states of synchro output we use a transformer with taps on thesecondary approximately equal to the synchro voltages at 15 degree intervals. Thevoltages are 0, 23, 45, 72, and 89 for a 90v system. They are less for other systemsbut in the same ratio. Page 1 of the schematic shows how the transformer taps areconnected to IC8 to 19 which are opto-coupled SCRs or AC solid state relays. Thesoftware selects the appropriate one to be switched on which then selects theappropriate transformer tap. IC 22 to 29 are controlled by software to select the

relative phase of the voltage. The result is the generation of an S1-S2 voltage andan S2-S3 voltage.

Each transformer tap has a 10 ohm limiting resistor and each section a fuse. Thesynchro output has 1 ohm resistor to aid measuring current and RFI filters.

Again note that is up to the software to control the switching of IC8 to 29. I leave it toyou to work out what happens if IC14 and IC19 were selected together. These IC’shave “zero turn off” and turn on at about 5v on the AC side. The software is writtenonly to change the control state at about maximum excursion of the reference voltagenever near zero crossing point. IC39 provides the reference to logic interface. The

zero crossing feature minimises any RFI problems.

The way that zero crossing switching affects the receiving synchro minimises stressand jerk on it for a new state rises from the zero crossing when it is not energised soit starts to move to a new position with weak voltage which increases.



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Microprocessor

The Dallas 80C320 features two UARTS for serial data input with instructionexecution at about 2.5 times the original Intel design. One advantage is that clockspeed may be kept low which minimises RFI/EMC problems. IC30 31 32 and 36must all be good for microprocessor to run the software in the eprom.

IC36 is a voltage and program run monitor known as a watchdog. If the 5v dips dueto power failure it stops the microprocessor and restarts it after power is restored.IC36 a MAX1232 must also receive frequent stimulation from the microprocessor.The software tickles the watchdog routinely but if this tickling stops (Failureaccidental short circuit)? for half a second the watchdog will bark and reset themicroprocessor.

The microprocessor shifts data into a serial to parallel shift register IC34 37 this beingthe required state of synchro output. Note that should the watchdog go to a resetcondition as at switch on and switch off the shift register is instantly clearedpreventing erroneous operation of the synchro drivers.

The alarm circuit includes buzzer bi-colour led and relay controlled by themicroprocessor program via IC42. The external alarm relay goes to alarm statewhen alarm is switched off. This is intentional. A remote alarm should have its owndisable facility.

EMC

I have made mention of the design features which minimise EMC. The ground planeof the pcb is another feature. All the tests we have made as with all other AMIproducts make it easy for us to certify the product as compliant with the EMCdirective.

MEASURING PHASE SHIFT ON OUTPUT

If at all possible we would like to check the phase shift due to reactive loading of thesynchro output. If it is significant we will have to fit capacitors to tune it out. It isimportant that this test is done on all new installations until we have built a data base

of what is found in practice. It requires a dual beam oscilloscope of no greatbandwidth. The usual engineer’s portable ‘scope will be fine.

Do this test from the start of putting the repeaters on line and certainly at the end withall repeaters connected.

Use the wires on the 1 ohm resistors R71 72 to make the connection.

Connect one channel probe to S1 its earth clip on S2 bottom end of R72 (it is alrightto earth S2 if it is a battery ‘scope all the better). This measures S1 - S2 voltage.



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Connect the second channel to the top end of R72. This measures the voltageacross the resistor to indicate S2 current.

Get a stable picture of two sine waves and draw it on paper. Please try to measureany phase shift between the two waveforms and fax us with your picture.

FINAL TEST PROCEDURE

This is a simple test procedure to prove the functioning of the KW903. It is not amethod of demonstrating all functions. A test engineer is free to make any furthertests he chooses.

CONNECTIONS

Connect to AC mains

Connect to Stepper input to Step Generator

Connect an NMEA heading source to NMEA input appropriate

Connect a PC to NMEA out

Connect a repeater to the synchro output

SWITCH SETTING: Switch to 0

Switch on. Confirm the audible alarm sounds.

Move the step input or 1:1 input very slowly. Confirm the repeater movessmoothly through 24 positions in one degree.

SELECT NMEA INPUT: Confirm the repeater follows an NMEA input.

SWITCH to “F”

Leave the KW903 exercising for at least one hour but as long as convenient. Checkthat nothing gets hotter than normal. From time to time switch back to “D” andconfirm the repeater follows smoothly.



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TRANSFORMER SETUP

1 4 0

1 1 0

0 1 4 0

1 1 0

0

1 4 0

1 1 0 0

1 4 0

1 1 0 0

1 4 0

1 1 0

0 1 4 0

1 1 0

0

V i o l e t

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O r a n g e

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V i o l e t

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B l a c k

W h i t e

V i o l e t

B l a c k

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W h i t e

V i o l e t

B l a c k

B l a c k

B l a c k

W h i t e

V i o l e t

B l a c k

B r o w n

G r e y

B l u e

B r o w n

G r e y

B l u e

B r o w n

G r e y

B l u e

B r o w n

G r e y

B l u e

S K 4

1 2 3 4

S K 4

S K 4

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1 2 3 4

S K 2

S K 2

S K 3

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V i o l e t

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S K 1

S K 2

S K 3

I N P U T : A S S E L E C

T E D

R E F E R E N C E O U T

: 1 1 2 V O L T S

M A X P H A S E O U T P U T : 8 6 V O L T S

U S E F O R 1 1 5 V R E F 9 0 V S I G

R E P E A T E R S Y S T

E M S

I N P U T : A S S

E L E C T E D

R E F E R E N C

E O U T : 5 0 V O L T S

M A X P H A S E

O U T P U T : 6 8 V O L T S

U S E F O R C - P L A T H 5 0 V R E F

6 8 V L - L S Y S T E M S

N O T E T H A T

8 8 V R E F C A N B E O B T A I N E D

B Y U S I N G W

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T H I S C A N B

E T R I E D O N 1 1 0 V / 6 0 V S Y S T E M S

1

2

3

P O W E R I N P U T

C O N N E C T O R

P O W E R I N P U T

C O N N E C T O R

P O W E R I N P U T

C O N N

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1 2 V

1 A

1 1 2 V

8 6 V

0 V

1 2 V

1 A

1 2 V

1 A

8 8 V

5 0 V

0 V

R E F E R E N C E S U P P L Y



T E R M I N A L B L O C K

O N C H A S S I S P L A T E

M E T

H O D O F U S I N G A S E C O N D T R A N S F O R M E R

T O O B T A I N D I F F E R E N T R E F E R E N C E V O L T A G E

U S E

K W 9 0 3 T R A N S F O R M E R C E 5 9 2 0 F O R

A N S

H U T Z 5 0 V / 2 0 V ( 6 0 V / 2 4 V R E P E A T E R S

U S E

E X T E R N A L S T E P U P / D O W N T R A N S F O R M E R

O R V A R I A C T O F I N E – T U N E O U T P U T V O L T A G E S .

T R A N S F O R

M E R S U S E T H E

B E L O W C

O L O U R S :

F R O M A V E L A R E B I - C O L O U R E D W I T H Y E L L O W

F R O M D A R

E N A R E B I - C O L O U R E D W I T H B L A C K

U N C O N N E C T E D W

I R E S

A R E T E R M I N A T E D I N

T H E T E M I N A L B L O C K S



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Manual KW903 SP Iss 04

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