NEETS 15 ch 1,4 Flashcards
What is the name given to a variety of rotary electromechanical, position sensing devices?
The synchro
What is the primary purpose of a synchro system?
Precise and rapid transmission of data between equipment and stations.
Name the two general classifications of synchro systems.
Torque and control.
What is the difference between a torque synchro and a control synchro?
A torque synchro is used for light loads and a control synchro is used in systems desired to move
heavy loads.
Using table 1-1, name two synchros that provide a mechanical output.
The torque receiver (TR) and the torque differential receiver (TDR).
What does the code 26V-11TX4D mean on a synchro nameplate?
It is the third modification of a 26-volt 400-hertz (torque) synchro transmitter whose bodydiameter is between 1.01 and 1.10 inches.
Which of the two synchro designation codes is indicated by 5DG on a synchro nameplate?
The Navy prestandard designation code.
On the synchro schematic symbol, what indicates the angular displacement of the rotor?
The position of the arrow.
What are the two major components of a synchro?
The rotor and the stator.
Which of the two main types of rotors can have either a single winding or three Y-connected
windings?
The drum or wound rotor
How does the stator receive its voltage?
By the magnetic coupling from the rotor
Where are the external connections made on standard synchros?
At the terminal board
What major factors determine the load capacity of a torque-synchro transmitter?
. The number and type of synchro receivers, the mechanical loads on these receivers and the
operating temperatures of both the transmitter and receivers
Define the term “torque.”
A measure of how much load a machine can turn.
What unit of measurement refers to the torque of a synchro transmitter?
Ounce-inches.
What type of equipment normally uses 26-volt 400-hertz synchros?
. Aircraft.
When will a synchro generate more heat than it is designed to handle?
When it is overloaded.
How do synchros differ from conventional transformers?
Synchros have one primary winding that can be turned through 360º and three secondary
windings spaced 120º apart.
Describe the zero-position of a synchro transmitter.
The transmitter is in its zero-position when the rotor is aligned with the S2 stator winding.
When is the maximum voltage induced into a stator coil?
. When the rotor coil is aligned with the stator coil
What three factors determine the amplitude of the voltage induced into a stator winding?
The amplitude of the primary voltage, the turns ratio, and the angular displacement between the
rotor and the stator winding
What is the physical difference between a synchro transmitter and a synchro receiver?
A synchro receiver uses some form of damping to retard excessive oscillations or spinning.
What method is used to prevent oscillations in large synchro units?
Mechanical damping.
What two components make up a simple synchro transmission system?
A synchro transmitter and a synchro receiver.
What leads in a simple synchro system are connected to the ac power line?
The rotor leads.
What is the relationship between the transmitter and receiver stator voltages when their rotors
are in correspondence?
The voltages are equal and oppose each other
What is the name given to the angle through which a transmitters rotor is mechanically rotated?
Signal.
What two receiver leads are reversed to reverse the rotor’s direction of rotation?
. 1 and S3.
What is the most likely problem if the transmitter shaft reads 0º when the receiver shaft indicates
180º?
. The rotor leads on either the transmitter or the receiver are reversed.
What is the purpose of using differential synchros instead of regular synchros?
. Differential synchros can handle more signals than regular synchros and also perform addition
and subtraction functions
What are the two types of differential synchros?
The TDX and the TDR
Other than their physical differences, what is the major difference between a TDX and a TDR?
Their application: a TDX has one electrical and one mechanical input with an electrical output.
What determines whether a differential synchro adds or subtracts?
The way the differential synchro is connected in a system is the deciding factor on whether the
unit adds or subtracts its inputs
In a TDX system when does the TR rotor follow the TX rotor exactly?
When the TDX rotor is on 0º.
What is the angular position of a TX rotor when it is pointing toward the S1 winding? (Hint.
Remember synchros are labeled counter clockwise from 0º.
240º.
In a TDX system with standard synchro connections, the TX rotor is at 120º and the TDX rotor is
at 40º. What position will the TR indicate?
. 80º.
What connections in a TDX system are reversed to set up the system for addition?
The S1 and S3 leads are reversed between the TX and the TDX, and the R1 and R3 leads are
reversed between the TDX rotor and the TR.
What connections in a TDR system are reversed to set up the system for addition?
The R1 and R3 leads between the TDR rotor and the TX to which it is connected
In a TDR system connected for addition in what direction will the TDR rotor field turn when the
TX rotor to which it is connected turns counterclockwise?
Clockwise.
What type of synchro is used in systems requiring large amounts of power and a high degree of
accuracy?
A control synchro
What are the three types of control synchros?
. CX, CT, and CDX.
How do the CX and CDX differ from the TX and TDX?
. The CX and CDX have higher impedance windings
What three things prevent a CT rotor from turning when voltages are applied to its stator
windings?
The rotor is specially wound, it is never connected to an ac supply, and its output is always
applied to a high-impedance load
When a CT is on electrical zero, what is the relationship between its rotor and the S2 winding?
They are perpendicular to each other
What is the amplitude and voltage induced into the rotor when the CX is turned 90º while the CT
remains on electrical zero?
The voltage is maximum and in phase with the ac excitation voltage to the CX.
What is the name given to the electrical output of a CT?
Error signal.
In a control synchro system, when is the output of the CT reduced to zero?
When the CX and CT rotors are in correspondence.
What is the purpose of the synchro capacitor?
To improve overall synchro system accuracy by reducing stator currents
What type of synchros usually require the use of synchro capacitors?
TDXs, CDXs, and Cts.
What type of current is eliminated by synchro capacitors?
Magnetizing current.
How are synchro capacitors connected in a circuit?
They are delta-connected across the stator windings
Why are synchro capacitors placed physically close to differentials transmitters and CTs?
To keep the connections as short as possible in order to maintain system.
What is the name given to the synchro system that transmits data at two different speeds?
A dual or double-speed synchro system.
What is the main reason for using a multispeed synchro system instead of a single-speed synchro
system?
. Greater accuracy without the loss of self-synchronous operation.
In a dual-speed synchro system what determines the two specific speeds at which the data will be
transmitted?
The gear ratio between the two transmitters.
What type of synchro system is used to transmit very large quantities?
A tri-speed synchro system
What is the disadvantage of using a double receiver instead of two individual receivers?
If one of the receivers goes bad the entire unit must be replaced
What is the purpose of “stickoff voltage”?
It is used in synchro systems to prevent false synchronizations
What is the reference point for alignment of all synchro units?
Electrical zero.
What is the most accurate method of zeroing a synchro?
The voltmeter method.
What is the purpose of the coarse setting of a synchro?
.It ensures the synchro is on 0º, not 180º
When is a synchro receiver (TR) properly zeroed?
A TR is zeroed when electrical zero voltages exist across its stator windings at the same time its
rotor is on zero or on its mechanical reference position
What should a voltmeter read when a TX is set on coarse zero?
Approximately 37 volts
What precaution should you take when you use 115 volts to zero a differential?
Never leave the circuit energized for more than 2 minutes
Why should a synchro be rechecked for zero after it is clamped down?
. To ensure that it did not move off zero while it was being clamped
What is the output voltage of a CT when it is set on electrical zero?
Zero or minimum voltage.
When you zero a multispeed synchro system which synchro should you zero first?
. The coarse synchro
What method of zeroing a synchro is perhaps the fastest but NOT necessarily the most accurate?
The electrical lock method
What restrictions are placed on the use of the electrical lock method?
It can be used only if the leads of the synchro are accessible and the rotor is free to turn.
When you zero a synchro with a synchro tester, what is indicated by a jump in the synchro tester’s
dial when the S1 and S3 leads are momentarily shorted?
. The synchro under test is not on electrical zero
What should you do with a synchro that has a bad set of bearings?
Replace it.
Name two types of trouble you would expect to find in a newly installed synchro system.
Improper wiring and misalignment
What type of indicator is usually placed in the stator circuit of a torque synchro system?
An overload indicator.
What is the most probable cause of trouble in a synchro system that has all of its receivers
reading incorrectly?
The transmitter or main bus
If an ac voltmeter is connected between the S2 and S3 windings on a TX, at what two rotor
positions should the voltmeter read maximum voltage?
150º and 330º
What precaution should you take when substituting a synchro tester in a circuit for a transmitter?
Use only one receiver so as not to overload the tester.
What is a servo?
Direction of rotation and amount of torque.
Compare the power sources of synchros and step-transmission systems.
Synchros use ac; step transmission uses dc.
A step transmitter is a modification of what electrical device?
Rotary switch
What type of mathematical problem is solved by resolvers?
Right-triangle, or trigonometric, problems.
