Description of the laboratory plant

The laboratory plant for research of aviation tachometers consists of a friction clutch Ф-1, a complete set of tachometric control plant КТУ-1М, laboratory bench and frequency meter Ч3-32. The friction clutch Ф-1 is the setting device of revolutions and is actuated by the electromotor, powered by rotating the batch switch with inscriptions “on” and “off”. The attachment of the verifying pickup is made to the left flange of the friction clutch. The change of speed is implemented with the help of a handwheel, arranged on a forward part of friction clutch.

On a laboratory bench voltmeter, amperemeter for measurement of line currents and voltages in a system “generator - synchronous engine” are established, which are connected by means of wires with tips.

There are three contacts, to which the output leads of three stator windings of the generator are connected and the other three contacts, to which the output leads of three stator windings of the synchronous engine are connected. These contacts incorporate with the help of strips with tips.

The handle, signed by symbol , allows changing an ohmic resistance in one of lines connecting the stator winding of the generator and an appropriate stator winding of the engine. The switch of partial progress I - II - III has three positions and controls the relay, which connects to the verified pickup the one indicator (in position I), and two indicators (in position II). There are also indicators of tachometers are located on a bench. Near to the bench the frequency meter ЧЗ -32 is arranged.

Order and methodic of the work execution

1. Connect measurement devices to appropriate parts of tachometer electric circuit by leads.

2. With change of pickup shaft rotation frequency measure linear current and voltage, and also AC frequency, when the tachometer pointer coincides with each digitized scale point. Enroll the results to table 2.

After finishing measurement set the tachometer indications to 0 % and after that turn off the plant.

Table 2

Tachometer readings, n%	Frequency, measured by frequency meter, Hz		Linear voltage, V	Linear current, mА	Calculated rotation frequency
	f '	f "	U l	I l	n'p	n"p
20
30
40
50
60
70
80
90

3. Calculate by the frequency meter readings appropriate values of pickup shaft rotation frequency by formulas:

n'_p = 1,2 * f ' ; n"_p = 1,2 * f " ;

4. Enroll calculated values of n'_p and n"_p to the table 2 and 3.

5. Calculate the tachometer absolute error on all the digitized points by formulas:

n'_p = n - n'_p ;  n"_p = n - n"_p ;

6. Calculate the variation of frequency measuring absolute error by formula:

Н = n'_p –  n"_p ;

Enroll calculated values of H to the table 3.

Table 3

Tachometer readings, %	Calculated rotation frequency, %		Absolute error of frequency measurement		Variation
n	n'p	n"p	n'p	n"p	H
20
30
40
50
60
70
80
90