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Synchros and Control Transformers

Synchros and Control Transformers . Lesson Topic 8.1. LESSON TOPIC 8.1 SYNCHROS AND CONTROL TRANSFORMERS, THEORY OF OPERATION. SYNCHRO AND CONTROL TRANSFORMER. Synchro Identification Type of function Frequency

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Synchros and Control Transformers

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  1. Synchros and Control Transformers Lesson Topic 8.1

  2. LESSON TOPIC 8.1SYNCHROS AND CONTROL TRANSFORMERS, THEORY OF OPERATION

  3. SYNCHRO AND CONTROL TRANSFORMER Synchro Identification Type of functionFrequency C = CONTROL 4 = 400hz T = TORQUE 6 = 60hz 1 6 T R 6 a DiameterModification in inches and tenths of a or no letter = Original inches (1.51” to 1.6”) Specific function D=Differential R=Receiver T=Transformer X=Transmitter

  4. LESSON TOPIC 8.1SYNCHROS AND CONTROL TRANSFORMERS, THEORY OF OPERATION SPECIFIC FUNCTION • LETTERDESIGNATION • D DIFFERENTIAL • R RECEIVER • T TRANSFORMER • X TRANSMITTER If the letter b follows the specific function designation the synchro has a rotatable stator. Ex. 1 6 T R b 6 a

  5. SEVEN BASIC FUNCTIONAL CLASSES • Torque Transmitter = TX • Torque Differential Transmitter = TDX • Torque Receiver = TR or TRX • Torque Differential Receiver = TDR • Control Transmitter = CX • Control Differential Transmitter = CDX • Control Transformer = CT • All torque systems will start with a “T”, transmitter have an “X” and receivers an “R”. • All control systems will have a “C” for control, transmitter have an “X”. • Torque and control synchro systems may NOT be interchangeable.

  6. Military Standard Synchro Code • Identification marking synchros. • Example:18CT6A

  7. Military Standard Synchro Code 18CT6A -Diameter -Represented in inches. • ex) 18 = 1.8 “

  8. Military Standard Synchro Code 18CT6A • First Letter • Synchro General Function • C – Control

  9. Military Standard Synchro Code 18CT6A • Second Letter • Specific Function • T – Transformer

  10. Military Standard Synchro Code 18CT6A • Frequency • Indicated by the last number. • 6 – 60HZ 18CT6A • Modification • Upper-case letter • Indicates how many times a synchro has been factory modified. • ex) A - Original synchro B - First modification etc.

  11. LESSON TOPIC 8.1SYNCHROS AND CONTROL TRANSFORMERS, THEORY OF OPERATION Synchros are rotary, electro-mechanical, position sensing devices, resembling a motor, that are used to convert mechanical signals to electrical or vice versa.

  12. SYNCHRO AND CONTROL TRANSFORMER • CHARACTERISTICS • Physical Synchros are simply variable transformer . Rotor – primary winding w/c maybe rotated 360 degrees. Stator – three stationary winding spaced 120 electrical degrees apart.

  13. SYNCHRO CONSTRUCTION • A typical synchro has 2 major components: • Rotor – composed of a single winding (R1, R2) receiving the excitation voltage from an external source. Salient-pole rotor Drum or wound rotor Just like motors and generators slip rings are attached to the rotor shaft, and the excitation voltage is applied via brushes.

  14. The stator is composed of three wye-connected windings (S1,S2,S3). Stators are very similar to the stator of a motor or generator. It is cylindrical in construction made of laminated material on which the stator windings are wound.

  15. SYNCHRO FUNDAMENTAL The synchro transmitter resembles a small bipolar 3-phase motor. The stator is wound with a 3 circuit, Y-connected winding. The rotor is wound with a single circuit winding.

  16. R-Rotor S-Stator BLOCK AND SCHEMATIC DIAGRAM OF A SYNCHRO The schematic symbols for the synchro transmitter and receiver are the SAME.

  17. Synchro Schematic SymbolsOn the synchro schematic symbol the position of the arrow indicates the angular displacement of the rotor in the figures C, D and E below the displacement is zero degrees.

  18. Synchro Fundamentals • 2 types of synchros. • Torque • Control

  19. Synchro Fundamentals • Torque synchros provide enough torque to position light loads. • Dial • Pointer • Control synchros provide a small signal that is used to position heavy loads. • gun turrets • missile launchers • Numerous synchro receivers

  20. SYNCHRO AND CONTROL TRANSFORMER (TR) (TX)

  21. BASIC SYNCHRO SYSTEM CONFIGURATION

  22. BASIC SYNCHRO SYSTEM CONFIGURATION The Stator of TX will mirror its induced magnetic field in the stator of TR Rotor is usually geared to a manual or mechanical input.

  23. BASIC SYNCHRO SYSTEM CONFIGURATION

  24. BASIC SYNCHRO SYSTEM CONFIGURATION

  25. CONTROL TRANSFORMER

  26. CONTROL TRANSFORMER

  27. SYNCHRO AND CONTROL TRANSFORMER

  28. SYNCHRO AND CONTROL TRANSFORMER

  29. SYNCHRO AND CONTROL TRANSFORMER

  30. SYNCHRO AND CONTROL TRANSFORMER

  31. Electrically Zeroing • Synchros must be electrically zeroed at installation in order to function in correspondence. • There are three methods. • Voltmeter • Electric Lock • Synchro Tester

  32. Voltmeter method • Safest • Most accurate • Most common method • Three Steps • Mechanical Zero (Step 1) • Entails aligning rotor to zero mark. • Coarse Zero (Step 2) • Ensures fine zero step is not 180 deg out of phase. • False Null. • Fine Zero (Step 3) • Ensures exact zero.

  33. Voltmeter Method (Step 1) • Mechanical Zero Procedure • Deenergize System. • Place dial pointer to the zero position. • Tape dial pointer down. • Disconnect Stator leads.

  34. Voltmeter Method (Step 2) • Course Zero Procedure • Connect a jumper between R-2 and S-3. • Connect meter leads between R-1 and S-2. • Loosen captive screws around synchro housing. • Only enough to allow movement of housing. • Set meter to volts AC scale. • Don PPE. • EnergizeSystem. • Turn housing until 37VAC reading is obtained. • Disconnect all meter leads and jumper.

  35. Voltmeter Method (Step 3) • Fine Zero Procedure • Deenergize System. • Connect meter leads between S-1 and S-3. • Set meter to volts AC scale. • Don PPE.

  36. Voltmeter Method (Step 3) • Energize System. • Turn housing until null reading is obtained. • Maximum reading 2.5 VAC. • De-energize System. • Return system to normal configuration. • Conduct system test.

  37. Electrically Zeroing • Electric Lock • Fastest method • Rotors must be free to turn • Caution: do not have system energized for more than 2 minutes.

  38. Electrically Zeroing • Synchro Tester • Primary function of synchro tester is to detect faulty synchros. • Can be used to zero synchros • Less accurate since the dial is graduated in ten degree increments.

  39. Common System Faults • Most synchro problems are related to wiring or alignment. • Poor installation. • Loose connections. • Broken leads or frayed cable. • Fault symptoms will be present either in all TRs or a single TR. • All TRs • Fault is in TX. • Single TR • Fault is in that TR.

  40. Seven Synchro Faults • Rotor Faults • Shorted Rotor • Open Rotor • Reversed rotor • Stator Faults • Shorted Stator • Open Stator • Reversed Stator • 3 Reversed Stator Pairs

  41. Rotor Faults • Short • Zero Torque • Blown Fuses • Open • Low Torque • May be 180 degrees out of correspondence. • Reverse • Normal torque • Always 180 degrees out of correspondence.

  42. Stator Faults • Short • High torque • Rotor is locked across good winding • Will affect all synchros in a system • Open • Normal torque • Rotor will oscillate between good windings • Note: always check synchro symptoms slowly to ensure accurate indication.

  43. Stator Faults • Reverse • Normal torque • Opposite rotation • Will correspond on good winding • 3 Reverse Stators • Normal torque • Same direction • Will lead or lag 120 out of correspondence.

  44. Troubleshooting Six step trouble shooting technique. • A strategic approach to troubleshooting • (1) Symptom recognition • (2) Symptom elaboration • (3) List probable faulty function • (4) Localize faulty function • (5) Localize faulty circuit • (6) Failure analysis

  45. Troubleshooting • (1) Symptom recognition • Consult tech manual on proper operation to determine if there is a fault. • Many times system is functioning properly • (2) Symptom Elaboration • Record specifics of symptom. • i.e. What, where, how many etc. • (3) List probable faulty function • Decide based on first 2 steps where the problem is. • TX or TR?

  46. Troubleshooting • (4) Localize the faulty function • Take readings and prove previous findings. • (5) Localize the faulty circuit • Using readings, determine exact point of fault. • (6) Failure Analysis • Always be able to explain how you fixed it to your chain of command or supervisor.

  47. Corrective Maintenance • Common practices when working with synchros. • Never disassemble a synchro. • Always replace defective synchros • Never lubricate a synchro • Never force a synchro into place.

  48. Synchros and Control Transformers • Summary

  49. QUESTIONS????

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