REK 50 protection of a synchronous machine User s Manual REK 50 X 0 9 8 7 6 5 4 0 V 00 V 0 V 5 6 7 Ordering No: REK 50-AA Uau = 00/0 Vac Un = 48 V Serial No: fn = 50/60 Hz Uec = ma 600 Vdc
MRS 75587-MUM Issued: 0.06.00 Version: A/0.0.004 REK 50 We reserve the right to change data without prior notice. Contents:. Application...4. Operation principle...5. Connection diagrams...7 4. Testing instructions...8 5. Technical data...9 6. Mechanical dimensions and mounting instructions... 6.. Dimensions... 6.. Mounting instructions... 7. References... 8. Order information...
REK 50 MRS 75587-MUM. Application The purpose of the earth-fault protection is to detect earth faults in the ecitation circuit of synchronous machines. The ecitation field circuit is isolated during normal operating conditions. The field circuit can be eposed to abnormal mechanical or thermal stress due to vibrations, overcurrent, choked cooling medium flow, etc. This may result in the breakdown of the insulation between the field winding and the iron at a point eposed to ecessive stress. A single earth fault is not very dangerous and does not cause immediate damage, because the fault current is small due to the low voltage. More dangerous is a second earth fault that appears as a winding interturn fault and causes severe magnetic unbalance and heavy vibrations leading to severe damage. Therefore, it is essential that any occurrence of an insulation failure is detected and that the machine is disconnected as soon as possible. Normally, the machine is tripped after a short time delay. For generators with slip rings the insulation resistance is sometimes reduced due to the accumulated carbon dust layer produced by the carbon brushes. This product replaces the current injection device type SPMK C40 C. 4
MRS 75587-MUM REK 50. Operation principle The injection device REK 50, supplied from a secured 0 V or 00 V 50/60Hz source, sets up a 48 V ac voltage via its coupling capacitors to the circuit towards earth. This auiliary ac voltage forms a small charging current to flow via the coupling capacitors, resistances of the brushes and earth capacitances of the field circuit. These field to earth capacitances C E affect the level of the resulting current, which is a few milliamperes during normal no-fault operating conditions. If an earth fault arises somewhere in the field circuit, this current increases and may reach a level of 65 ma at a fully developed earth fault (fault resistance R E = 0 Ω). The integrated current transformer of the REK 50 then amplifies this current with the ratio :0 to a measurable level even with relays that have a A rated current input. A definite time earth-fault relay, e.g. REJ 5 is connected to measure this current. The relay used should be insensitive to harmonics as a considerable amount of harmonics can occur in the current, especially with thyristor ecitation and rotating diode rectifier systems. If the machine terminal REM 54/5 is used, dual-stage earth-fault protection can be achieved using the non-directional E/F functions NEFLow and NEFHigh, set to operate in a fundamental frequency mode. In this mode, digital filtering is used to filter out dc and harmonic components that could produce false alarms/trips. 0 V I C 5 R B 00 V C 6 7 SM ~ R B C E R E 0 V T T REK 50 I Rm/ Rm/ E/F Relay rek50procdiagr Fig..- Principle of the earth-fault protection for the eitation field circuit with ac current injection. 5
REK 50 MRS 75587-MUM Typically, the alarm level for weakly developed earth faults is set to a current pickup level corresponding to a fault resistance of 0 kω, with a time delay of 0 sec. Tripping for fully developed earth faults is set to a current level corresponding to a fault resistance of - kω, with a 0.5 sec delay. rec50protcurr_0a Fig..- Fig.. Protection current measured by REM 54 as a function of the earth-fault resistance with various field-to-earth capacitance values, measuring circuit resistance R m = 0.Ω, f n = 50 Hz. rec50protcurr_ Fig..- Fig.. Protection current measured by REM 54 as a function of the earth-fault resistance with various field-to-earth capacitance values, measuring circuit resistance R m =.0 Ω, f n = 50 Hz. 6
MRS 75587-MUM REK 50. Connection diagrams L L L 0 - PC Uau 0 V ac 00 V ac X REK 50 C T C T X 5 6 7 X BI X. X. 7 8 A 0.A L G L- Uau ~ ~ - IRF 4 5 I - O SO SO 0 7 8 9 PO PO 5 6 4 MKC95000- Optical PC-interface 5 SGB 6 SGB IRF Io> START Blocking of stage Io> TRIP Io>> START Blocking of stage Io>> TRIP SGR SGR SGR SGR4 4 4 SGB INDICATIONS CLEARED = Factory Default SGB SGB 4 SGB OUTP. CONT. UNLATCHED AND INDIC. CLEARED I/O MEMORIZED VALUES AND INDIC. CLEARED; OUTPUT CONTACTS UNLATCHED SWITCHGROUP SELECTION ConD_5_rek50_dp Fig..- Double-pole connection. Connection to both winding ends is recommended as it gives the most accurate measuring results. L L L 0 - PC Uau 0 V ac 00 V ac X REK 50 C T C T X 5 6 7 X BI X. X. 7 8 A 0.A L G L- Uau ~ ~ - IRF 4 5 I - O SO SO 0 7 8 9 PO PO 5 6 4 MKC95000- Optical PC-interface 5 SGB 6 SGB IRF Io> START Blocking of stage Io> TRIP Io>> START Blocking of stage Io>> TRIP SGR SGR SGR SGR4 4 4 SGB INDICATIONS CLEARED = Factory Default SGB SGB 4 SGB OUTP. CONT. UNLATCHED AND INDIC. CLEARED I/O MEMORIZED VALUES AND INDIC. CLEARED; OUTPUT CONTACTS UNLATCHED SWITCHGROUP SELECTION ConD_5_rek50_sp Fig..- Single-pole connection.if only one end of the winding can be connected to the REK 50, terminals 5 and 6 have to be linked together. 7
REK 50 MRS 75587-MUM 4. Testing instructions L L L 0 - PC Uau 0 V ac X REK 50 C T C T X S 5 R E 6 7 X BI X. X. 7 8 A 0.A L G L- Uau ~ ~ - IRF 4 5 I - O SO SO 0 7 8 9 PO PO 5 6 4 MKC95000- Optical PC-interface 5 SGB 6 SGB IRF Io> START Blocking of stage Io> TRIP Io>> START Blocking of stage Io>> TRIP SGR SGR SGR SGR4 4 4 SGB INDICATIONS CLEARED = Factory Default SGB SGB 4 SGB OUTP. CONT. UNLATCHED AND INDIC. CLEARED I/O MEMORIZED VALUES AND INDIC. CLEARED; OUTPUT CONTACTS UNLATCHED SWITCHGROUP SELECTION TstD_5_rek50_sp Fig. 4.- Test connections For testing purpose an adjustable potentiometer R E (0 0 kω, 0.6 W), which simulates earth fault, is connected in series with a test switch S between the connectors X(5) and earth X(7). The protection relay itself should be tested according to the instructions given in the relay manuals. 8
MRS 75587-MUM REK 50 5. Technical data Supply voltage, range according to IEC 6055-6 Output voltage, nominal Short-circuit current between connected terminals 5 and 6 against terminal 7 Ma. ecitation voltage withstand from terminals 5 and 6 to terminal 7 Maimum current of protection unit (terminals -) Maimum measuring circuit resistance of the protection unit (terminals -) 0 V or 00 V -0% 0%, 50/60 Hz 48 Vac I = 80 ma; withstands continuous short circuit 600 V dc I 800 ma R m Ω Coupling capacitors µf Power consumption.5 W Degree of protection provided by enclosure IP 0 of the device according to IEC 59 Weight of the unit.8kg Environmental tests and conditions Service temperature range IEC 6055-6 -0 C 55 C Transport and storage temperature -40 C 70 C IEC 6055-6 Dry cold test according to IEC 60068-- -0 C Dry heat test according to IEC 60068-- 55 C Damp heat test, cyclic according to IEC 60068-- Storage temperature test according to IEC 60068--48 Dielectric tests Dielectric test according to IEC 6055-5 Input to outputs, output to output and all to earth 5 C 55 C, RH > 9% 6 cycles ( -hour cycle) -40 C 70 C.kV 50Hz min Impulse test according to IEC 6055-5 7. kv. µs /50 µs Insulation resistance measurement according >00 MΩ, 500 V dc to IEC 6055-5 Electromagnetic compatibility tests MHz burst disturbance test according to IEC 6055-- Electrostatic discharge test according to IEC 6055--, IEC 6000-4- Radio frequency interference tests: Conducted, according to IEC 6055--6, IEC 6000-4-6 Radiated, amplitude-modulated, according to IEC 6055--, IEC 6000-4- Radiated, pulse-modulated, according to ENV 5004, IEC 6055-- Fast (5/50 ns) transient disturbance test according to IEC 6055--4, IEC 6000-4-4.5 kv common mode.0 kv differential mode 6 kv contact discharge 8 kv air discharge 0 V (rms) f = 50 khz...80 MHz 80% amp. mod. with khz sinewave 0 V/m (rms) f = 0...000 MHz 80% amp. mod. with khz sinewave 0 V/m, f = 900 MHz f =.89 GHz Rep. frequency = 00 Hz, duty cycle 50% 4 kv 9
REK 50 MRS 75587-MUM Power frequency (50 Hz) magnetic field test according to IEC 6000-4-8 Surge immunity test according to IEC 6055--5, IEC 6000-4-5 Electromagnetic emission tests Conducted rf emission EN 550 (EN 550), EN 6055-5 Radiated rf emission EN 550 (EN 550), EN 6055-5 Mechanical tests 00 A/m 4 kv common mode kv differential mode class A mains Vibration tests IEC 6055-- class Shock and bump tests IEC 6055-- class class A enclosure 0
MRS 75587-MUM REK 50 6. Mechanical dimensions and mounting instructions 6.. Dimensions Fig. 6..- Dimensional drawing REK_mittapiirros 6.. Mounting instructions The unit is enclosed in a metal case designed to be attached to the wall with four M6 size screws. Eternal connections have to be done according to the connection diagram. The numbering of the contacts runs from bottom to top. The screw-compression type terminal block X is dimensioned for one ma. 6 mm or two ma..5 mm wires. A separate earth lead (.5 mm ) should be connected from the earth screw to the earth bar. No soldering is needed.
REK 50 MRS 75587-MUM 7. References Technical Reference Manual REJ 5 MRS75099-MUM Technical Reference Manual REM 54_ MRS75095-MUM
MRS 75587-MUM REK 50 8. Order information Injection device REK 50 for earth fault protection REK 50-AA
ABB Oy Distribution Automation P.O. Bo 699 FI-650 Vaasa FINLAND Tel. 58 0 Fa. 58 0 4 094 www.abb.com/substationautomation MRS 75587-MUM EN 06.004