Generator Protection Alstom Micom p343 Testing Procedure

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Information about Generator Protection Alstom Micom p343 Testing Procedure

Published on November 18, 2016

Author: davidroy39

Source: slideshare.net

1. DR GENERATOR PROTECTION MICOM P343 TESTING PROCEDURE Generator details received from customer Rating = 7.5MW AT 0.8 p.f = 9.375 MVA Terminal Voltage = 11KV Synchrous Reactance Xd = 1.94pu = 1.94 x 11 x 11 /9.375 = 25.0 ohm Transcient Reactance Xd’ = 0.162 pu = 0.162 x 11 x 11 /9.375 = 2.1 ohm Sub Transcient Reactance Xd’’ = 0.147 pu = 0.147 x 11 x 11 /9.375 = 1.90 ohm CT/PT Details Generator phase side CT ratio = 600A/1A. Generator neutral side CT ratio = 600A/1A. Generator PT ratio = 11KV/ 110V (Phase to Phase) Generator CT / PT ratio = 6 Continuous NPS withstand capacity = 15% Neutral Grounding Resister Details Voltage Ratio = 11KV / 110 V Current Ratio = 100 A/ 1A Note: The setting has been formulated as per the details received from the customer. All the settings are in secondary values.

2. DR GENERATOR DIFFERENTIAL PROTECTION (87G) Generator full load current = 9.375 MVA/ √3 x11000V = 492A With respect to secondary current = 492A/600A = 0.82A Settings: Since we are setting the relay as Biased Differential we use the following setting. Minimum pick up current (IS1) =10% The first slope for the differential for fault current nearer to rated current (k1) = 0% (To achieve maximum sensitivity the value is set to zero or no bias.) The pick-up setting at which bias is changed to higher slope (IS2) = 120% (to allow consistent sensitivity for all internal faults) The slope of the bias characteristics to take care of severe faults (IS2) = 150% (To achieve clear discrimination for minor unbalance caused during extreme fault condition) Active settings Group 1 GenDiff Function Percentage Bias Gen Diff Is1 100mA (For maximum winding coverage) Gen Diff k1 0% (For maximum sensitivity) Gen Diff Is2 1.2A (To allow consistent sensitivity for all internal faults) Gen Diff k2 150.0% Connection diagram for biased differential test

3. DR Testing Procedure: Ø Slowly increase the current I1 until the relay operates whilst leaving I2 at 0 Amps. Record the operating current I1 in the table provided. Ø We have now assessed the minimum sensitivity of the relay. This gives an indication of the current required to cause operating for a genuine internal fault. Notice that the relay does not operate at exactly the Is1 setting but at a value slightly higher. This is due to a small amount of bias being generated by the I1 current, which inevitably raises the relay setting. The actual minimum sensitivity is given by the following equation:- Minimum Pick-up current = Is1 k12 Is1k1 + - ´ Ø The next phase of testing a bias differential relay is to establish that the bias characteristic matches the relay settings. This is done by adjusting the magnitude of the two anti-phase currents (I1 and I2) until the relay operates. At the point of operation the differential and bias currents can be calculated and plotted to see if they correlate with the relay settings. This test is explained below. Ø Apply the initial currents stated in the table and then slowly increase current I1 until the relay operates. Note the current at which the relay operates (in “I1 Trip” column), calculate the bias and differential currents and then plot them on the graph provided. Note that the per phase bias and differential current can be observed in the MEASUREMENTS 3 column. Initial I1 I2 I1 Trip Bias Current = (I1 Trip + I2)/2 Differential Current = I1 Trip – I2 0 0 0.3 Ð0° 0.3 Ð0° 0.4 0.35 0.1 0.6 Ð0° 0.6 Ð0° 0.7 0.65 0.1 1.2 Ð0° 1.2 Ð0° 1.6 1.4 0.4 1.4 Ð0° 1.4 Ð0° 3 2.2 1.6 1.5 Ð0° 1.5 Ð0° 3.7 2.6 2.2 Ø For the lower bias slope the formula below can be used to determine the differential operate current (enter k1 slope in pu form, i.e. percentage/100): Phase operate current is (Is1 + IBias x k1) pu +/- 10% Ø For the upper bias slope the formula below can be used to determine the differential operate current (enter k1 and k2 slopes in pu form, i.e. percentage/100): Operate current is [(IBias x k2) + {(k1 – k2) x Is2 } + Is1] pu +/- 20%

4. DR If the test has been performed correctly the recorded results should closely match those shown above. The plot clearly shows that the relay increases it’s setting as the through fault current increases, thus minimising the chances of mal-operation due to CT saturation. Had we tested the high impedance or interturn differential then we would see that the setting does not increase with through fault current. This is because high impedance protection relies upon an external resistor for stability rather than bias. The interturn differential is normally connected via core balance CT’s which are not susceptible to saturation affects which cause problems with the high impedance or percentage bias schemes. 0 0.5 1 1.5 2 2.5 3 3.5 0 0.5 1 1.5 2 2.5 3 3.5 DifferentialCurrent(Amps) Bias Current (Amps) Expected Characteristic

5. DR REVERSE POWER PROTECTION (32) Assuming more than 2% of power level could result in dangerous over speed transients on loss of electrical loading. Power1 Function : Reverse -P>1 Setting : 30.00 W (Selected the lowest setting) Power1 TimeDelay : 5.000 s (To prevent false tripping or Alarms being during power system disturbances or synchronisation) Power1 DO Timer : 0 s Poledead inh : Enabled Connection diagram for 3 phase power tests Ø Apply the following voltages: Va = 50VÐ0°, Vb = 50VÐ-120°, Vc = 50VÐ120° Ø Apply the following currents: Ia = 0.1AÐ180°, Ib = 0.1AÐ60°, Ic = 0.1AÐ-60°. This represents a reverse power of 15W (0.1 x 50 x 3). Ø Increase all three currents until the relay operates. Operation should occur at approximately 0.2A, which is equivalent to the 30W setting (0.2 x 50 x 3). Note that the setting is a 3 phase power quantity. Note the 3 Phase power measurement can be observed in the MEASUREMENTS 2 column. Ø This test has proved the reverse power threshold is correct. The next step is to establish that the characteristic is a symmetrical.

6. DR Ø Disconnect the timer stop leads from the relay then apply the same voltages, with the following currents: Ia = 1AÐ180°, Ib = 1AÐ60°, Ic = 1AÐ-60°. Note that the relay operates strongly as the power (150W) is well within the operating region of the characteristic. Ø Rotate the phase angle of the three currents clockwise, maintaining their 120° phase relationship, until the relay stops operating. This is indicated by the “Any Start” LED switching off (LED 8). Reset the trip indications and then rotate back in to the characteristic until the relay operates once again. Note this angle down. Ø Repeat the previous step except rotate anti-clockwise this time. Once again note the angle. The measured angle should be equal indicating the characteristic is symmetrical, as shown in the Figure Reverse power characteristic Ø Selecting “Motoring” in the “Operating mode” cell inverts the active power measurement. This effectively reverses the power characteristic so that it would appear on the “+W” side. Ø The next step is test the “Power1 DO timer”. This stops the “Power1 Time Delay” timer from resetting if the power momentarily exits the characteristic. Fluctuating power is common with diesel engines prime mover failures. By setting a time delay on reset the relay may still operate even if the power fluctuations are severe. Modify the following settings: Power1 Time Delay: 10 s & Power1 DO Timer: 10s Ø Re-connect the timer stop leads to the relay then apply the following voltages: Va = 50VÐ0°, Vb = 50VÐ-120°, Vc = 50VÐ120° Ø Apply the following currents and check that the relay operates in 10 seconds: Ia = 0.5AÐ180°, Ib = 0.5AÐ60°, Ic = 0.5AÐ-60°. Ø Switch off the current for at least 12 seconds and then re-apply the fault. Note that the relay will once again operate in 10 seconds. This proves that the “Power1 Time Delay” is correct and that the relay is fully resetting following the “Power1 DO Timer”. Figure ‘a’ shows the operation of the relay under this condition. RESTRAIN RESTRAIN Power Setting -VAr 15W TRIP -W TRIP q2° q1° q1 = q2 150VA +VAr +W

7. DR The next stage is to prove that the relay operating level is held for the “Power1 DO Time”. This is done by applying a reverse power condition for, say, 5 seconds followed by a forward power condition for 2 seconds and then a reverse power condition once again. If the relay operate level is held correctly, when the fault is re-applied the operating time will be shorter. In theory the operating time should be equal to the “Power1 Time Delay” setting minus the duration of the first fault application. However, in practice the operating time may be even shorter as most test sets take a finite length of time to move from a forward power condition to reverse power condition and back again. This means that the relay may be in the reverse power condition longer than expected. Figure ‘b’ illustrates the relay behaviour for these fault conditions. Application of fluctuating reverse power Ø Apply the following currents for approximately 5 seconds: 0.5AÐ180°, Ib = 0.5AÐ60°, Ic = 0.5AÐ-60°. Then rotate the currents by 180° for roughly 2 seconds and then return them. The relay operating time should be less than 5 seconds once the fault is re-applied, indicating the relay has paused the operation timer instead of resetting it. LOW FORWARD POWER PROTECTION (37) When a machine is generating and the CB connecting the generator to the system is tripped, the electrical load is cut. This could lead to the generator over-speed if the mechanical power is not reduced quickly. When non-urgent faults occur, such as a stator earth fault on a high impedance earthed machine, it may be prudent to disconnect the prime mover before opening this CB. Tripping of the circuit breaker occurs when the output power has fallen to sufficient levels so as to minimise the possibility of overspeed. This process is know as low forward power interlocking. The following section is a simple demonstration of this feature Power2 Function : Low forward P>2 Setting : 12 W Power 2 TimeDelay : 2.000 s (Not to prevent non-urgent electrical tripping in the event of power fluctuations arising from sudden steam valve / throttle closure) Power 2 DO Timer : 0 s P2 Poledead inh : Enabled

8. DR Ø Apply the following voltages: Va = 50VÐ0°, Vb = 50VÐ-120°, Vc = 50VÐ120° Ø Apply the following current: Ia = 0.2AÐ0°, Ib = 0.2AÐ-120°, Ic = 0.2AÐ120°. This represents a forward power of 30W. Ø Slowly decrease the current until the relay operates. Operation should occur at approximately at 0.08A. This corresponds to a 3 phase forward power of 12W. FIELD FAILURE PROTECTION (40) Complete loss of excitation may arise as a result of accidental tripping of the excitation system or even open circuit or short circuit faults occurring the DC system. Loss of the excitation causes the internal emf to collapse and the reduction of active power output. Under this condition the generator can over-speed and draw reactive power from the system. The difference in speed between the rotor and the system causes low frequency currents to flow in the rotor circuit, which may result in damage to the machine depending upon its construction. The P342 and P343 utilises a mho characteristic to detect this condition and disconnect the machine if appropriate. We will be testing the field failure alarm and the first stage of the field failure characteristic. Field failure characteristic Xa1 Xb1 Alarm Angle Xc Xa1 -R Xb1 Alarm Angle +R XL = 20 ohms = 220 ohms = 15°

9. DR Transformation ratio : CT Ratio/ PT Ratio : 6 Diameter of circle : Xd x 6 : 25.0 x 6 : 150 ohm Offset : 0.5 x Xd’ x 6 : 0.5 x 2.1 x 6 : 6.3 ohm FFail Alm Status Enabled FFail Alm Angle 15.00 deg Ffail Alm delay 5.00s This setting is equivalent to a power factor of 0.96 leading and need to be checked with operating power factor at normal running conditions. FFail1 Status Enabled FFail1 -Xa1 20 Ohm (-Xa1 = 0.5 Xd’ in secondary ohms) FFail1 Xb1 220 Ohm (Xb1 = Xd in secondary ohms) FFail1 TimeDelay 10.00 s FFail1 DO Timer 2 s FFail2 Status Disabled The first part of the test is to prove the operating boundary of the field failure alarm: Ø Apply the following voltage and current: Va = 100VÐ0°, Ia = 1.0AÐ0°. Ø Rotate the current (current leads volts) until the relay display the “FFail Alarm” on the LCD accompanied by the yellow alarm LED. This should occur at roughly +15°. Ø Rotate the current in the opposite direction (noting that alarm resets), until the alarm operates once again. Operation should occur at roughly 165°. We will now prove the field failure characteristic: Disable the field failure alarm by modifying the following setting as follows :- FFail Alm Status Disabled Ø Apply the following voltage and current: Va = 100VÐ0°, Ia = 0.25AÐ+90°. The applied impedance is at position “A” of the polar diagram as shown in the figure. Ø Increase the current until the relay operates. This should occur at roughly 0.42A (100V/(220+20)) and indicates that we are now at the outer edge of the circle – point “B” (Xa1+Xb1). Ø Increase the current to 0.5A. The relay should be operating strongly as the relay impedance is now at point C. Ø Rotate the phase angle of the current anti-clockwise until the relay drops off and it is possible to reset it. Slowly rotate the current phase angle clockwise until the relay just operates again. Record the phase angle between the current and voltage (q1 on the polar diagram).

10. DR Ø Without changing the magnitude of the current and voltage, rotate the current phase angle clockwise, passing through the operating area, until once again it is possible to reset the relay. Slowly rotate the current phase angle anti-clockwise until the relay again just operates. Measure the new angle, q2 on the polar diagram. Ø The relay characteristic angle is the mean of the two measured angles and should be roughly 0°. Ø Apply the following voltage and current: Va = 10VÐ0°, Ia = 1.0AÐ+90°. The applied impedance is at position “D” of the polar diagram. Ø Slowly increase the voltage until the relay again just operates. This should occur at 20V (20ohm/1Amp). The relay impedance is now at point “E”, thus proving that the characteristic has the correct dimensions and position.

11. DR Polar diagram of field failure characteristic Negative phase sequence thermal protection(46) Overloads can result in stator temperature rises that exceed the thermal limit of the winding insulation. Empirical results have shown that the life of the insulation is halved for each 10°C rise in temperature above the rated value. However, the life of the insulation is not wholly dependent upon the rise in temperature but on the time the insulation maintained at this elevated temperature. This means that short overloads may cause little damage to the machine whereas sustained overloads may cause extensive damage to the windings and insulation. Unbalanced load will also give rise to rotor heating due to the negative sequence created. The P343 relay models the time-current thermal characteristic of a generator by internally generating a thermal replica of the machine. Both the positive and negative sequence currents are combined together to form an equivalent current (Ieq). We will be testing the thermal characteristic with both positive and negative sequence currents. Assuming the continuous NPS withstand of the generator = 15% Thermal time constant = (according to customer) I2>1 Alarm Enabled I2>1 Current Set 90mA I2>1 Time Delay (as given by customer) I2>2 Trip Enabled I2>2 Current Set 120mA I2>2 k Setting 10 I2>2 kRESET 10 I2>2 tMAX (This value has been chosen with the assumption that the machine can withstand 0.5 pu of unbalance for a period of 30 sec. If thermal withstand characteristic is available the setting should be modified accordingly.) I2>2 tMIN (This setting has to be chosen as to co-ordinate with Zone 3 of distance protection / dead time setting of autorecloser / CB pole discrepancy timer, whichever is higher.

12. DR Connection diagram for thermal tests Ø Locate the MEASUREMENTS 3 column and then scroll down to display the “Thermal Overload” measurement. Ø Apply the following currents to the relay: Ia = 1.0AÐ0°, Ib = 1.0AÐ-120°, Ic = 1.0AÐ120°. Notice that the relay thermal measurement reaches roughly 63.2% after 1 minute (1 time constant) and 86.5% after 2 (2 time constants) minutes this time. This proves that the relay is correctly modelling the exponential temperature rise of the protected plant (cable, transformer etc.). Switch the current off after 2 minutes. Had we injected current for 5 minutes the relay thermal level would have reached 100% and eventually tripped. Ø Locate the “Reset ThermalO/L” cell in the MEASUREMENTS 3 column and then select yes to reset. Notice that the thermal level has reset to 0%. The next step is to establish the relay operating time for an overload condition. Ø Apply the following currents and wait for the relay to trip: Ia = 2.0AÐ0°, Ib = 2.0AÐ-120°, Ic = 2.0AÐ120°. The relay should trip and display a thermal trip in approximately 17.3 seconds. Ø The relay operating time is given by the following equation :- ÷÷ ø ö çç è æ - - ´= 1Ieq IpIeq Logτtop 2 2 e Where: Ieq = > + IThermal I2I1 22 M Ip = >IThermal loadPrefault I1 = Positive sequence current I2 = Negative sequence current M = Negative sequence multiplier Thermal I> = Thermal Setting t = heating time constant in seconds

13. DR Therefore with no negative sequence: Ieq = 01 032 22 . ´+ = 2A With no pre fault current the operating time (top) is calculated as follows :- ÷÷ ø ö çç è æ - - ´= 12 02 Log06top 2 2 e = 17.26 seconds Now that we have proved the relay operating time, the next step is to prove the cooling time constant. This is done as follows:- Ø Locate the “Reset ThermalO/L” cell in the MEASUREMENTS 3 column and then select yes to reset. Ø Apply the following currents and wait for the relay to trip: Ia = 2.0AÐ0°, Ib = 2.0AÐ-120°, Ic = 2.0AÐ120°. Once again the relay should trip in approximately 17.3 seconds. Ensure that the current is switched off as soon as the relay trips. Ø Wait for one “cooling” time constant, also 60 seconds, and then re-apply the same current to the relay. Notice that the relay operating time is roughly 11 seconds (63.2% of 17.26 seconds). The reduced operating time is due to the thermal level not reaching zero before the fault is re- applied. The following figure illustrates this behaviour. Relay thermal state for intermittent faults Ø Locate the “Reset ThermalO/L” cell in the MEASUREMENTS 3 column and then select yes to reset.

14. DR We will now test the relays behaviour when negative sequence is applied instead of positive sequence :- Ø Apply the following currents and wait for the relay to trip: Ia = 2.0AÐ0°, Ib = 2.0AÐ120°, Ic = 2.0AÐ-120°. The injected currents represent 2A of pure negative sequence. The relay should trip and display a thermal trip in approximately 5.22 seconds. The relay operating time is given by the following equation: Therefore with no negative sequence: Ieq = 01 230 22 . ´+ = 3.46A With no pre fault current the operating time (top) is calculated as follows :- ÷÷ ø ö çç è æ - - ´= 1463 0463 Log06top 2 2 e . . = 5.22 seconds Notice that the relay operating time is significantly reduced when negative sequence is applied. This is due to the “M Factor” which increases the effect of negative sequence. 100% STATOR EARTH FAULT PROTECTION Standard residual current or voltage protection elements can only protect 95% of the stator winding. Earth faults in the final 5% of the winding will result in such low fault current and voltage imbalance that conventional protection cannot be relied upon to detect the fault. The P343 provides employs a technique whereby the relay looks for changes in the amount of third harmonic being produced by the generator. Under normal conditions the third harmonic voltage is distributed evenly along the stator winding. During an earth fault the in the final 5% of the winding the third harmonic voltage will rise significantly at the generator terminals. If the VT were connected at the generator terminals the third harmonic voltage rise could be detected. However, if the voltage from a neutral earthing VT were applied to the relay then this would see the third harmonic voltage collapse. Therefore the relay has two settings, these are overvoltage mode for a terminal VT and undervoltage mode for a neutral earthing VT. We will be testing the 100% stator earth fault protection in both overvoltage and undervoltage modes: The following headings will be used to perform this task :- CONFIGURATION (Enabling “100% Stator EF” function) GROUP 1 100% STATOR EF (Protection settings for 100% stator EF) Ø Locate the CONFIGURATION column and then enable “100% Stator EF”. Ensure that all other protection functions are disabled in this column. Ø Locate the GROUP1 100% STATOR EF column and then apply the following settings:

15. DR 100% St EF Status VN3H> Enabled 100% St EF VN3H> 20V VN3H> Delay 0 s Connect the circuit as shown in the Figure Connection diagram for 100% stator EF tests Ø Using the tests set apply 15V at 150Hz. Slowly increase the voltage until the relay operates and indicates a 100% stator EF trip. Operation should occur at 20V. Ø Reduce the voltage to 15V the reset the relay. This proves that the relay will operate if the VT is connected on the generator terminals. The next stage is to check operation if a neutral earthing VT was used. This is done by selecting the element to be undervoltage instead of overvoltage. It is also necessary to apply a voltage to the normal voltage inputs so that the relay assumes the generator is energised. Remember that a reduction in 3rd harmonic may be due to the generator being de-energised instead of an actual earth fault. Modify the following settings: 100% St EF Status VN3H< Enabled 100% St EF VN3H> 1.000V V< Inhibit Set 80 V P< Inhibit Disabled Q< Inhibit Disabled S< Inhibit Disabled Ø Using the tests set apply 5V at 150Hz. Ø Using the variac apply 110V to the phase voltage terminals.

16. DR Ø Slowly decrease the voltage on the test set (150Hz) until the relay operates. This should occur a roughly 1 volt and proves the 3rd harmonic undervoltage is working correctly. Ø Switch off the variac and check that it is possible to reset the relay. This ensures that the under voltage inhibit feature is correctly functioning. Unfortunately due to limitations in the test equipment it is impossible for us to test the under power inhibits on the 100% stator earth fault protection. The under power inhibits wok in exactly the same way as the under voltage inhibit except that there needs to be a certain amount of Watts, VA and VAr’s flowing before the protection is enabled. GENERATOR AT STAND STILL CONDITION I have attached another example with the formula for this particular test Voltage from the 20 Hz signal generator measured at TB terminal in the panel after voltage divider circuit: 3.9 V Voltage measured at NGT terminal: 1.23 V Voltage measurement at relay: 1.63 V Relay measured current: 5.8 to 5.9 mA Relay measured current angle: 93.01 degree Relay measured secondary resistance: 9 to 13 k ohm Relay measured primary resistance: 247 to 336 k ohm V divider ratio= (voltage across NGT terminal / voltage measured in relay) POLE SLIPPING PROTECTION Sudden changes or shocks in the electrical power system such as line switching operations, large jumps in load or faults may lead to system oscillations which appear as regular variations of the currents, voltages and angular separation between systems. This phenomenon is referred to as a power swing. In a recoverable situation, the power swing will decay and finally disappear in a few seconds. Synchronism will be regained and the power system will recover to stable operation. In a non- recoverable situation, the power swing becomes so severe that synchronism is lost between the generator and the system. If such a loss of synchronism does occur it is imperative to separate the generator from the rest of the system before damage occurs. The P343 provides a lenticular impedance characteristic which is used to detect pole slips. If relay detects the system impedance passing through the characteristic at a certain speed and direction then a trip will be given. The full criterion for operation is as follows:-

17. DR Generating mode (machine acting as a generator): Pole slip mode must be set to “generating”. Impedance starting from point R1 enters characteristic and stays roughly at R2 for at time greater than the “PSlip Timer T1” and then enters R3. The impedance must stay around R3 for at least the “PSlip Timer T2” before exiting in to R4. If this sequence is not followed or each region is exited before the timers expire then relay will not trip. Motoring mode (machine acting as a motor): Pole slip mode must be set to “motoring”. Impedance starting from point R4 enters characteristic and stays roughly at R3 for at time greater than the “PSlip Timer T1” and then enters R2. The impedance must stay around R2 for at least the “PSlip Timer T2” before exiting in to R1. If this sequence is not followed or if the impedance exits each region before the timers expire then relay will not trip. Both generating and motoring (machines can operate as generator or motor) Pole slip mode must be set to “motoring”. Operation can occur in either the generating or motoring sequences are followed. The regions R1 to R4 are shown in figure together with an illustration of the relay settings. We will be proving the characteristic shape as well as the relay ability to detect a genuine pole slip condition. The following headings will be used to perform this task :- CONFIGURATION (Enabling “Pole Slipping” function) GROUP 1 POLE SLIPPING (Protection settings for pole slipping) Pole slip characteristic

18. DR Ø Locate the CONFIGURATION column and then enable “Pole Slipping”. Ensure that all other protection functions are disabled in this column. Ø Locate the GROUP1 POLE SLIPPING column and then apply the following settings: PSlip Function Enabled Pole Slip Mode Generator PSlip Za Forward 100 Ohms PSlip Za Forward 150 Ohms Lens Angle 120 deg PSlip Timer T1 15.00 ms PSlip Timer T2 15.00 ms Blinder Angle 75 deg PSlip Zc 50 Ohms Zone 1 Slip Count 1 Zone 2 Slip Count 2 PSlip Reset Time 30.00 s We will now prove the shape of the characteristic before we test its ability to detect pole slips. Ø Connect the circuit as shown in the Figure. Ø Modify the PSL so that the LED mappings are as shown in Figure. Each LED represents a certain location on the pole slipping characteristic. E.g. LED 1 = Pole slip detected in Zone 1 (Zone 1 start) LED 2 = Pole slip detected in Zone 2 (Zone 2 start) LED 3 = Lens start (impedance has entered the lens characteristic) LED 4 = Blinder start (impedance is to left of the blinder) LED 5 = Reactance start (impedance is below the reactance line) PSL for LED mappings

19. DR The operation of pole slipping start/trip signals can be shown in the Test Port Status cell in the Commission Test menu. The 8 Test Port bits can be set to the appropriate DDB number using the Monitor Port 1-8 menu cells (Pslipz Z1 Trip – DDB497, Pslipz Z2 Trip – DDB498, Pslipz Z1 Start – DDB645, Pslipz Z2 Start – DDB646, Pslipz LensStart – DDB647, Pslipz BlindStrt – DDB648, Pslipz ReactStrt – DDB649). Ø Apply the following voltages: Va = 50VÐ0°, Vb = 50VÐ-120°, Vc = 50VÐ120° Ø Apply the following currents: Ia = 0.6AÐ0°, Ib = 0.6AÐ-120°, Ic = 0.6AÐ120°. This represents an impedance of 80W Ð0°. The impedance is now at point “A” on the polar diagram in figure. Notice that LED 5 is ON, indicating that the impedance is below the reactance line. Ø Rotate the angle of the current (I lead V) until LED 3 illuminates (in addition to LED 5) indicating that the impedance has entered the lens. This should occur at roughly 42°. The impedance is now at point “B”. Ø Continue to rotate the current until the impedance crosses the blinder at 105° indicated by LED 4 illuminating. The impedance is now at point “C”. Switch off the current and voltage and notice that the LED’s turn off. Ø Without modifying the voltage, apply the following currents: Ia = 0.6AÐ180°, Ib = 0.6AÐ60°, Ic = 0.6AÐ-60°. This represents an impedance of 80W Ð180°. The impedance is now at point “E” on the polar plot. Notice that LED’s 4 and 5 illuminate. Ø Decrease the angle of the current (towards point “D”) until the relay LED 3 illuminates. This should occur at approximately 168° and indicates that the impedance is at position “D”. Once again switch off the current and voltage noting the LED’s turn off. Ø Reapply the current and voltage indicated in “i”. Notice that LED’s 4 and 5 are turned on. The impedance is now back at point “E”. Rotate the current towards “F” until LED 5 switches off, which should occur at roughly 234°. The impedance is now at point “F” (i.e. above the reactance line, but to the left of the blinder). Ø Continue to rotate the current in the same direction until LED 3 illuminates once again indicating that we have re-entered the lens at point “G”. The LED should illuminate at approximately 259°. Switch off the current and voltage noting that LED’s turn off. Ø Leaving the voltage at the same values apply the following currents: Ia = 0.6AÐ0°, Ib = 0.6AÐ- 120°, Ic = 0.6AÐ120°. Once again the impedance is back at “A” on the polar diagram. Note that only LED 5 will be illuminated as we are once again below the reactance line. Ø Rotate the current (I lag V) towards point “J”. Note that LED 5 turns off indicating that the impedance is at point “J”. This should occur at roughly –24°. Ø Continue to rotate the current in the same direction until LED 3 illuminates indicating that the impedance is at point “I” and within the lens. The LED should illuminate at approximately -49°. Ø Once again continue to rotate the current in the same direction until LED 4 also illuminates and the impedance is at point “H”. For correct operation the LED should illuminate at approximately –75°.

20. DR Pole Slipping Test The previous test was used to prove the lenticular impedance characteristic that the relay uses to detect pole slips. The next test will simulate a genuine pole slip condition, which will prove the pole slip counters and timers. The pole slip will be simulated using the omicron control centre, which incorporates a program script that tells the omicron to inject a sequence of pre-defined impedances. The program script will have several variables, which we can change, and this allows us to inject any pole slip that we require. The pole slip locus we will inject is shown in figure. Xc Zone 2 XL Zone 1 & Zone 2 ZB = 150 ohms Blinder Zone 1 & Zone 2 Zone 2 Reactance line B C D F G J A H E I 42° 105° 168° 234° 259° R-R -24° -49° -75°

21. DR Pole Slip Locus Ø The relay should already have the correct settings, as in step b.) of the previous test. Ø Connect the circuit as shown in Figure. Ø Open the omicron control centre program provided by double clicking on following icon on the desktop: Ø From the “view” menu in the window select “script view” and ensure the following parameters are set as shown below. Zone 2 XL Zone 2 R Xc Zone 1 & Zone 2 Pole Slip Locus ZB = 150 ohms 31°25° A B ZA = 100 ohms ZC = 50 ohms Zone 1 & Zone 2 C Reactance line

22. DR Ø Compile the script. Do this using the “test” menu and selecting “user command”. Close the script window. Ø Pushing the “play” button on the toolbar will initiate the test sequence. The LED sequence should be as follows. As the test starts LED 5 should come ON, indicating that the impedance is below the reactance line. As the impedance hits Point “A” LED3 should also come ON, indicating that the impedance has entered the lens. LED 4 will come ON as the impedance hits point “B”, indicating that the impedance has crossed the blinder. Finally as the impedance goes through point “C”, LED 1 and 2 will come ON, indicating a pole slip in Zones 1 and 2, LED 3 will turn OFF, indicating that the impedance has left the lens and also the relay will TRIP. The pole slip applied to the relay rotates anti-clockwise at 50° per second. The impedance presented to the relay will take approximately 0.62 seconds to traverse from point A to point B and then 0.5 seconds from point B to C. Since both of these times are in excess of the PSlip Timer T1 and PSlip Timer T2 the relay will operate. Ø Clear the sequence on the control center by pushing the “X” button next to the “play” button on the toolbar. Ø In the script, change the “angle_direction” variable to –1. This indicates that the pole slip characteristic will now rotate clockwise. Start the sequence as before and it should be noticed that the relay does not recognise this condition as a pole slip and does NOT TRIP. Ø Locate the GROUP1 POLE SLIPPING column and then apply the following settings: Pole Slip Mode Motoring Ø Re-start the test again and it should be noticed that the relay now trips. This is because a generator in motoring mode will see a pole slip in the reverse direction. Ø Change the parameters in the script to that shown below. This sets the parameters to perform 2 pole slips. Locate the GROUP1 POLE SLIPPING column and then apply the following settings: Pole Slip Mode Generating Zone 1 Slip Count 2 The relay is now set to operate after 2 pole slips instead of 1. Ø Compile the script again and push the “play” button. It should be noticed that the relay repeats the LED sequence in step “e.)” twice and after the second rotation the relay will TRIP

23. DR Ø We will now prove the timer operation of the relay. Set the script back to the values as in step “c.)”. From the script it can be seen that the step time is 0.1secs and the step count degree is 5. This means that the impedance travels 5 degrees every 100mS. Therefore, from figure it can be seen that R2(point A to point B) is 31degrees and R3(point B to point C) is 21degrees. Ø So the time it takes for the impedance to travel through R2 is ((31/5)*0.1) = 620mS Ø Likewise for R3 its ((25/5)*0.1) = 500mS Ø If the impedance does not pass through the region in a time slower than the Pslip timers T1 and T2 are set to then the relay does not recognise this as pole slip. Ø Locate the GROUP1 POLE SLIPPING column and then apply the following settings: PSlip Timer T1 700 ms PSlip Timer T2 600 ms Note that the impedance will pass through the two regions before each of the timers time out. Ø Running the test will now result in a NO TRIP condition. 95% Stator earth fault protection(51G) IN Input Measured IN>1 Function DT IN>1 Current Set 40mA. (5% of full load current) IN>1 Time Delay 3.000 s (Maximum with stand time) IN>1 tReset 0 s IN>2 Status Enabled IN>2 Function DT IN>2 Current 1.5A (150% of limited earth fault current) IN>2 Time delay 0s Voltage Restraint over current(51V) The voltage dependent over current function is used for system backup protection and can trip the generator circuit breaker, if a fault has not been cleared by other protection after a certain period of time. The voltage dependent function can be either voltage controlled or voltage restrained. When voltage controlled, the timing characteristics of voltage drop is set below the set level. It is mainly used for Generators connected directly to the bus bar when voltage restrained, the current pick-up level is proportionally lowered as the voltage falls below a set value, producing a continuous variation of timing characteristics. This is applicable to Generators connected to the bus bar, each via step-up transformer.

24. DR VOLTAGE CONTROLLED MODE VOLTAGE RESTRAINED MODE Back up function Voltage restraind Vector Rotation None V Dep OC Char IEC S Inverse V Dep OC I> Set 0.88 A V Dep OC TMS 1.000 (Need to coordinate with downstream relays) V Dep OC tRESET 0 s V Dep OC V<1 Set 80.00 V V Dep OC V<2 Set 66.00 V V Dep OC k Set 0.40 (If transmission line parameters are available you can use that value, else assume the value) VOLTAGE PROTECTION These settings are used as backup for failure of AVR or other regulations. The time settings depends upon the withstand levels of the machine. Stage 1: Under voltage at 80% Stage 2: Over voltage at 120% Stage 2: Over voltage at 130%

25. DR UNDER VOLTAGE (27) V< Measur't Mode Phase-Neutral V< Operate Mode Any Phase V<1 Function DT V<1 Voltage Set 51.00 V V<1 Time Delay 3.00 s V<1 Poledead Inh Enabled V<2 Status Disabled OVER VOLTAGE (59) V> Measur't Mode Phase-Phase V> Operate Mode Any Phase V>1 Function DT V>1 Voltage Set 132.0 V V>1 Time Delay 3.00 s V>2 Status Enabled V>2 Voltage Set 143.0 V V>2 Time Delay 0.0 s The voltage settings are tentative and need to be checked with the permissible limits of the machine FREQUENCY PROTECTION (81U/O) UNDER FREQUENCY F<1 Status Enabled F<1 Setting 48.50 Hz F<1 Time Delay 5.000 s F<2 Status Enabled F<2 Setting 47.50 Hz F<2 Time Delay 1.000 s F<3 Status Disabled F<4 Status Disabled OVER FREQUENCY F>1 Status Enabled F>1 Setting 51.00 Hz F>1 Time Delay 2.000 s F>2 Status Enabled F>2 Setting 52.00 Hz F>2 Time Delay 1.000 s These settings are tentative and need to be co-ordinated with normal and transient over frequency excursions following full load rejection.

26. DR BREAKER FAIL PROTECTION CB Fail 1 status Enabled. CB Fail 1 timer 200ms. CB Fail 2 status Disabled. CBF Non I Reset CB Open & I< CBF Ext Reset CB Open & I< UNDER CURRENT I<Current Set 40mA VT SUPERVISION(60FL) VTS Status Blocking VTS Reset Mode Manual VTS Time Delay 5.000 s VTS I> Inhibit 12.00 A VTS I2> Inhibit 240.00mA Note: Voltage, frequency, breaker fail, vt supervision tests can be done as per normal methods which are very easy to follow. Kindly refer my previous uploads for details regarding the same.

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