1. Aim of the work: to get acquaintance with a work of protection functions of microprocessor-based relay protection device “MP3C-05”.

2. Tasks:

1. To get acquainted with a description, settings, logical schemes and a work of protection functions: maximal current protection (MT3), shortening protection (33), voltage protection (311), automatic frequency discharge (АЧР) of microprocessor-based relay protection device “MP3C-05” accordingly to exploitation manual РСГИ.466452.007 РЭ.

2. To get acquainted with Instruction of the operator of service program SizifJL, which is dedicated for a work with “MP3C-05” device.

3. To perform practical check of working accuracy of protection functions: maximal current protection (MT3), shortening protection (33), voltage protection (3H), automatic frequency discharge (АЧР) of microprocessor- based relay protection device “MP3C-05” using Sizif_L service program for parameter set.

4. To prepare a report with obtained results.

3. Theoretical data

   1. Setting of protection functions of mp3c-05

Protection functions of MP3C-05 are aimed for protection of air and cable voltage lines of 6 - 35 kV, which works with isolated or compensated neutral terminal:

• from phase shortening (MT3);

• from ground shortening (33);

• via minimal voltage (3H) ( with ability of current blocking selection and without blocking);

• via maximal voltage (311);

• from decrease of network frequency below desired (АЧР).

2. General guidance

MP3C device is produced by producer-plant fully adjusted and checked without protection functions, and with minimal values of settings, which values are presented in table 1.

It is necessary to configure MP3C-05 (turn on necessary protection subsystem MT3, 33, 311, АЧР), define functions of signal indicators, define functions of inputs (ДВ01 ...ДВ08) and outputs (P02...P07) ofMP3C and also set working settings and time restraints for performing of practical check of protection functions. Diagnostics of MP3C work, configuration, settings, defining of signal indicator functions, defining of input & output functions of MP3C device, and also control of output signal values are executed by means of Monitor program, which is built- in to the PERMANENT MEMORY of MP3C device.

Simplified scheme of connections

Simplified scheme of connections of MP3C-05 is described on fig. 1.

4. Work order

   1. Performing of practical check of protection functions MT3, 33, ЗН, АЧР of MP3C-05 device include the stage of parameter set for protection work of MP3C-05, sending of output voltage & current values in specified ranges, with the help of console panel, to input of MP3C-05 and also control of an accuracy of definite protection parameter measuring.

   2. Measured indications and their measuring accuracy

Measured indications and their accuracy is shown in table 1.

Table 1.

Measured parameter	Nominal value or measuring boundaries	Maximal deviation
Current of maximal current protection actuation (MT3),
A	0,50 - 20,00	±5%
Coefficient of a return (KB) of starting organs MT3	0,95-0,98	-
Restraint time of protection activation , s:
- 1 range	0,00-5,00	±0,01
- 2 range	5,00- 32,00	±0,05
Current of ground shortening protection actuation (33),
mA	5,00 - 300,00	±10%
Voltage of minimal voltage protection actuation	14,40 - 100,00	±5%
(Umhh), V
Voltage of maximal voltage protection activation	23,20 - 110,00	±5%
(Umakc), V
Coefficient of a return of voltage protection:
- Umhh	1,01 - 1,05	-
- UMakc, not less	0,9	-
Frequency of actuation and return of automatic
frequency discharge (АЧР), GHz	45,00 -50,00	0,05
Coefficient of a return of АЧР	1,01	±1%

During practical check of protection functions work (защит MT3, 33, 3H, АЧ) we calculate coefficients of the return, diagnostics tolerance of separate parameters by means of next formulas:

• coefficient of return of protection according to a current

Where I, - current of return of a protection to initial value;

And I_pra - current of protection actuation;

-coefficient of return of protection according to a voltage

Where U_r-voltage of return of protection to initial state;

And U_pra -voltage of protection actuation;

• Coefficient of return of a protection according to a frequency

Where f_r- frequency of return of protection to initial state; And f_pra- frequency of protection actuation;

• 

  - accuracy of actuation of voltage protection

  

  Where U_pra- voltage of protection actuation;

  And U_s — setting of a voltage of protection actuation;

  - coefficient of frequency protection actuation

  Accuracy of actuation of current protection

Where I_pra- current of protection actuation;

And I_s- setting of a current of protection actuation;

Where f_pra- frequency of protection actuation;

And f_s- setting of a frequency of protection actuation