4 Home task

1. To study theoretical material using the literature [2.1…2.5] and methodical instructions to this work

• pecularities of structure and functional constructing of rectifying devices;

• pecularies and limitations, put on schemotechnical realization of separate functional nodes of rectifying devices;

• processes of functioning in the rectifying devices;

• pecularities of laboratory stand;

• processes of functioning of researched multi-phase circuit of rectification in different working.

4.2 To prepare the protocols, where the information for processing of this lab Work is represented.

4.3 To study the function of each element of the rectifying, purpose of each experiment, expected results of the research.

4.4 Answer the control questions

Table 3.2 – Researched parameters

Notation	Oscilograms ofelectrical processes
ТV1, U1	Voltage u1(t) of primary transformer`s winding ТV1
TV1, I1	Current i1(t) of primary transformer`s winding ТV1
TV1, U2	Voltage u2(t of secondary transformer`s winding ТV1
TV1, I2	Current i2(t) of secondary transformer`s winding ТV1
VD1, U	Voltage uVD1(t) on the diode VD1
VD1, I	Current iVD1(t) of the diode VD1
VD2, U	Voltage uVD2(t) on the diode VD2
VD2, I	Current iVD2(t) of the diode VD2
VD3, U	Voltage uVD3(t) on the diode VD3
VD3, I	Current iVD3(t) of the diode VD3
VD4, U	Voltage uVD4(t) on the diode VD4
VD4, I	Current iVD4(t) of the diode VD4
Rн, U	Voltage uн(t) on the load RL
Rн, I	Current iн(t) of the load RL
Р0 U	Voltage uВ(t) on the output of rectifying block
Р0 I	Output current iВ(t) of rectifying block
C1, U	Voltage uС1(t) on the capacitor С1
C1, I	Current iС1(t) of the capacitor С1
C2, U	Voltage uС2(t) on the capacitor С2
C2, I	Current iС2(t) of the capacitor С2
L1, U	Voltage uL1(t) on the throttel L1
L1, I	Current iL1(t) of the throttel L1

5 Control questions

5.1 Why is inductive load preferred in multiphase circuits of rectification? 5.2 What forms of currents are in the secondary and primary windings of the transformer of single-cycle three-phase rectification circuit having an inductive load?

5.3The same as for point 5.2 for two-phase bridge rectification circuit.

5.4 What impact does the inductance of scattering of the transformer on the form of currents in the phases of the secondary windings and the shape of the output voltage? Explain the example of single-cycle three-phase rectification circuit having a load of inductive nature.

Таble 3.3 – Contant of laboratory stand
Pos.	Type of element	Regulated parameters				Comment
		The parameter	min	max	Unit
G1	Three-phase generator	Phase voltage	198	242	V	Effective value, operative regulation
		frequency	50	400	Hz
TV1	Three-phase transformer	Transformation coefficint	5	15
		Resistance of the secondary winding	0,1	1,5	Ом	Active resistance
		Inductance of scattering	0,1	1	мГн
VD1	Diode
VD2	Diode
VD3	Diode
VD4	Diode					Only for the 2nd scheme
VD5	Diode					Only for the 2nd scheme
VD6	Diode					Only for the 2nd scheme
L1	Throttel	inductance	0,01	10	Гн
Rн	Resister	resistance	5	200	Оhm	Operative regulation
SW1	Switch	State	off	on		Switch of the load
PV1	Voltmeter	State	off	on		Switch of the load
PV2	Voltmeter					Effective value
PV3	Voltmeter					Average value
PA1	Ampermeter					Effective value
PA2	Ampermeter					Effective value
PА3	Ampermeter					Average value
P0	Control point

5.5 What is the shape of the rectified voltage at the load of six-phase bridge circuit of rectification?

5.6 Explain to the graphs of the external characteristics of multiphase rectification circuits

5.7 How is the efficiency of the investigated schemes for rectification and whether can it be determined experimentally using a laboratory stand?

5.8 How is the coefficient of usage by power in primary, secondary winding, as well as in the whall transformer in each of the rectification with inductive load?

5.9 By what parameters are diodes for rectifying multi-phase circuits selected?

5.10 Give a comparative assessment of the basic parameters and indicators of quality for the investigated schemes of rectification.

5.11 Show on time-diagrams of current through the load constant component of current through the load for each of the circuits in Fig. 3.2 and Fig. 3.3.

5.12 What are the disadvantages and advantages of each of the given schemes?

5.13 What is the angle of overlapping of phases?

5.14 What parameters the angle of overlapping of phases depends on?

5.15 How to determine the value of reverse voltage across rectifier diodes?

5.16 What is the external characteristic of the rectifier?