RARIC User’s guide Shaft current protection - ABB Group · relay can be used for generators with...
Transcript of RARIC User’s guide Shaft current protection - ABB Group · relay can be used for generators with...
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RARICShaft current protection
• Sensitive protection for bearings of large rotating machines
• Operates for shaft currents larger than 0.4 - 1.0 A AC, depend-ing on the diameter of the shaft
• Fundamental or third harmonic operating principle
• AC or DC powered, galvanically isolated
• Shaft current transformer with test winding
• Can be applied to shafts with diameters up to 2960 mm
• Settable time delay
• Trip relay with heavy duty contacts and indicating flag
• Test switch
Features
User’s guide1MRK 502 001-UENRevision: BIssued February 2004
Data subject to changewithout notice
COPYRIGHT
WE RESERVE ALL RIGHTS TO THIS DOCUMENT, EVEN IN THE EVENT THAT A PATENT IS ISSUED AND A DIFFERENT COM-MERCIAL PROPRIETARY RIGHT IS REGISTERED. IMPROPER USE, IN PARTICULAR REPRODUCTION AND DISSEMINATION TO THIRD PARTIES, IS NOT PERMITTED.
THIS DOCUMENT HAS BEEN CAREFULLY CHECKED. IF THE USER NEVERTHELESS DETECTS ANY ERRORS, HE IS ASKED TO NOTIFY US AS SOON AS POSSIBLE.
THE DATA CONTAINED IN THIS MANUAL IS INTENDED SOLELY FOR THE CONCEPT OR PRODUCT DESCRIPTION AND IS NOT TO BE DEEMED TO BE A STATEMENT OF GUARANTEED PROPERTIES. IN THE INTERESTS OF OUR CUSTOMERS, WE CONSTANTLY SEEK TO ENSURE THAT OUR PRODUCTS ARE DEVELOPED TO THE LATEST TECHNOLOGICAL STAN-DARDS. AS A RESULT, IT IS POSSIBLE THAT THERE MAY BE SOME DIFFERENCES BETWEEN THE HW/SW PRODUCT AND THIS INFORMATION PRODUCT.
Manufacturer:
ABB Automation Technology Products ABSubstation AutomationSE-721 59 VästeråsSwedenTelephone: +46 (0) 21 34 20 00Facsimile: +46 (0) 21 14 69 18Internet: www.abb.com/substationautomation
1MRK 502 001-UENPage 2
RARICShaft current protection
Contents Page
1 APPLICATION ........................................................................... 3
2 DESIGN........................................................................................ 4
2.1 The RARIC protection ..................................................... 4
2.2 The ILDD shaft current transformer .............................. 5
3 MODE OF OPERATION ........................................................... 6
4 RECEIVING, STORAGE AND INSTALLATION ................. 8
4.1 Receiving ............................................................................ 8
4.2 Storage................................................................................ 8
4.3 Installation ......................................................................... 8
5 SETTING, TESTING AND COMMISSIONING .................... 9
5.1 Setting................................................................................. 9
5.2 Testing and commissioning .............................................. 95.2.1 Injection test ............................................................ 95.2.2 Primary test ............................................................. 9
6 MAINTENANCE ........................................................................ 9
7 TECHNICAL DATA ................................................................ 10
8 DIAGRAMS ............................................................................... 12
9 DIMENSION ILDD .................................................................. 15
10 MOUNTING ............................................................................. 16
RARICShaft current protection
1MRK 502 001-UENPage 3
1 APPLICATION
An emf is induced in the shaft of the generators due to the magnetic dis-similarities in the armature field. The emf normally contains a largeamount of harmonics. Both the wave-shape and the magnitude of theinduced voltage depend on the type and size of the machine and they alsovary with the loading.Normally, the induced voltage will be in the range 0.5 to 2 volts for turbo-generators and 10 to 30 volts for hydro-generators.
To prevent the rotor from being electrically charged, the shaft of the turbo-generators is usually grounded via a slip-ring on the prime mover side. Forhydro-generators, the water in the turbine provides a connection toground. If the bearing pedestal at the other side of the rotor is grounded,the induced voltage will be impressed across the thin oil-film of the bear-ing. Due to the low impedance of the loop formed by the shaft, the bearingand the ground structure, a breakdown of the oil-film insulation may giverise to a heavy current which leads to destruction of the bearing.
Consequently, the bearing pedestal furthest from the prime mover is usu-ally insulated from ground and the insulation should be supervised by asuitable protection. Severe damage on the bearings is not expected tooccur if the shaft current is less than one ampere.
Shaft current protection RARIC with a special current transformer ILDDis used to detect currents that can damage the bearings of a generator. Therelay can be used for generators with shaft diameter up to 2960 mm.Min operate current is 0.4 to 1.0 ampere, depending on the diameter of theshaft.
The RARIC protection is available in two versions:Version 1 has a linear frequency characteristic and operates on the funda-mental and harmonic components in the shaft current.
Version 2 has a damping filter for the fundamental frequency and operateson the harmonics in the shaft current. This version is used when the shaftcurrent transformer is exposed to a large fundamental frequency leakageflux.
1MRK 502 001-UENPage 4
RARICShaft current protection
2 DESIGN2.1 The RARIC protection
The RARIC protection is built up of a test switch, terminal bases, plug-inmodules and connection parts of type COMBIFLEX. The test switch andthe terminal bases are screwed to two apparatus bars. The plug-in modulesare inserted and screwed to the terminal bases. All internal connections aremade on the rear of the terminal bases with COMBIFLEX socket leads.Leads with a 10 A COMBIFLEX socket at one end are used for externalconnections to the relay bases and leads with 20 A socket are used for con-nections to the test switch.
Fig. 1 shows the components of the RARIC protection and the connec-tions to the measuring and test windings of the ILDD shaft-current trans-former. The numbers below refer to the numbering of the components inFig. 1.
1. Test switch RTXP 18When a test handle RTXH 18 is inserted into the test switch, the trip and alarm circuits are opened. A relay test apparatus can be con-nected to terminals 3B and 4B on the test handle to inject current into the test winding A - B.
2. Damping filter RXTFB 4 (only for RARIC, Version 2)contains capacitors, reactors and resistors. One parallel resonance and one series resonance circuit in the filter gives the frequency char-acteristic shown in Fig. 4.
3. Overcurrent relay RXIK1is the measuring unit of RARIC. The operating value of RXIK 1 is steplessly settable 0.5 - 2 mA. The current input circuit has an resist-ance of 82 ohms and contains an RC circuit to suppress high fre-quency disturbance signals. The output circuit contains an impulse holding function which ensures operation also when intermittent input current signals are received.
4. Time relay RXKL 1is a static relay with scale 30 ms to 99 h. The setting determines the delay of the trip signal.
5. Auxiliary relay RXME 18has heavy-duty contacts which can be used in signal and tripping cir-cuits. The relay is fitted with a red flag to indicate operation.The flag is manually reset by means of a resetting knob in the cover.
6. Power supply unit RXTUB 2is an AC/DC converter which contains a transformer, full-wave recti-fier and smoothing capacitors. The unit supplies auxiliary voltage to the relays in RARIC.The output DC voltage is 24 volts (± 12 V).
RARIC is also available with a DC/DC converter RXTUG 22H for DC auxiliary voltage supply.
RARICShaft current protection
1MRK 502 001-UENPage 5
ALARM
TRIP 17A16A
1
5
2.2 The ILDD shaft current tr
Fig. 1 Basic circuit for RARIC.
The ILDD shaft-current transformer is of special design with high qualitycore steel, where the number of secondary turns and the core cross-sec-tional area are optimized to the diameter of the transformer to get the low-est possible primary operate current when connected to the RXIK 1 relay.
The measuring and the test windings are covered with cotton tape and thenembedded in a circular shaped U-profile for mechanical protection andmagnetic screening. The profile with the core and the windings is thenembedded in resin.
The transformer is split up in two parts for sizes with inner diameter up toand including 2 000 mm. For larger diameters, the transformer is split upin four parts. When the parts are jointed, the steel sheets of the core areinterleaved with an overlap of about 30 mm.
The measuring winding, with 400 - 800 turns depending on the diameterof the transformer, is evenly distributed on the parts of the core. When thetransformer parts are mounted together, the parts of the measuring wind-ing must be connected to the terminals S, see Fig. 2. The pilot-wires to theRARIC protection are connected to terminals S1 -S2, see Fig. 2.
The test winding has four turns and is connected to terminals markedA and B.
-+ ++ 010
0V11
0V22
0V
18A2A 1A
1:
9A 10A
11A
12A
3
64 + 0 -
2
3A3B
4A4B
S1
S2
B
A
1
Ι
Ι
Ι
502001-5
ansformer
1MRK 502 001-UENPage 6
RARICShaft current protection
3 MODE OF OPERATION
Fig. 2 Shaft current transformer ILDD with diameter D up to 2000 mm.
The ILDD shaft current transformer encompasses the rotor shaft and func-tions in principle like a cable current transformer. The measuring winding,which is connected to the RARIC protection, contains from 400 up to 800turns, depending on the diameter of the transformer. When the current inthe measuring winding exceeds the operate value of the overcurrent relayRXIK 1, it operates and tripping is given after the delay set on time relayRXKL 1.
If the shaft current is intermittent, for example due to intermittent break-down of the insulation of the oil film in the bearing, pulses are fed toRXIK 1. If these pulses exceed the operating value of the relay, and theintervals between the pulses are shorter than 0.9 s, the contacts of the out-put relay will be continuously closed.
The impedance of the current measuring circuit in RXIK 1 is about 80ohms. Hence, for Version 1, the operate voltage is about 40 mV at the low-est setting 0.5 mA of RXIK 1.
Fig. 3 shows the maximum primary operate current at 50 - 60 Hz forRARIC, Version 1, at relay settings 0.5 and 1 mA as function of the innerdiameter of the ILDD transformer.Fig. 4 shows the operate voltage for RARIC, Version 2, as function of thefrequency. The curves in both figures are valid for sinusiodal currents andmax. 5 ohms pilot-wire resistance between the transformer and the protec-tion.
Max
70
38
50
D±5
A Q Tr afo A B B
A
S2S1S
en02000670.vsd
S
RARICShaft current protection
1MRK 502 001-UENPage 7
Fig. 3 Primary operate current at relay setting 0.5 resp. 1 mA as func-tion of the inner diameter of ILDD.
The filter in Version 2 rejects the fundamental voltage by more than 70:1.
Fig. 4 Operate voltage of RARIC, Version 2 as function of frequency. Rated frequency = 50 Hz.
en04000027
7
6
1
0,5
0,1
0,04
(V)
30 50 100 150 500
I = 1 mAs
I = 0,5 mAs
f (Hz)
502001-2
1MRK 502 001-UENPage 8
RARICShaft current protection
4 RECEIVING, STORAGE AN4.1 Receiving
4.2 Storage
4.3 Installation
Remove the protection from the transport case and make a visual inspec-tion for transport damages. Check that all screws are firmly tightened andall relay elements are securely fastened.
Check on the rating plate of the relay units that the delivered relay has cor-rect data as regards auxiliary voltage, frequency etc. Check against the listof apparatus that all units are included.
If the relay is to be stored before installation this must be done in a dry anddust-free place, preferably in the original transport case.
The RARIC protection can be placed in a 19" equipment frame for mount-ing in a 19" rack in a cubicle. The relay can also be placed in a relay casetype RHGX.
On delivery, all internal connections in the protection are ready made.External connections (dotted lines on the circuit diagrams) are made withleads with 20 A COMBIFLEX sockets to the RTXP 18 test switch andwith 10 A sockets to the relay terminal bases.
The ILDD shaft current transformer should be mounted around the shaft ata place where any possible current through the bearing is flowing in theshaft. This means that it should be mounted at the rotor side of any bearingor slip-ring. To avoid disturbances the transformer shall be mounted on theturbine side of the machine which is free from field bars and at maximumdistance from the end of the stator winding. See Fig. 12 and Fig. 13 forrecommended mounting.
Screened cable, with twisted pairs and with the screen grounded only atthe relay side is recommended for the connections between the protectionand the shaft current transformer.
An inner diameter of the transformer 20 - 50 mm larger than the shaftdiameter is suitably selected. Large diameter of the transformer has a neg-ative influence on the sensitivity of the protection and it also increases therisk of stray fluxes entering the CT core.
The width of the transformer in axial direction is 38 mm for inner diame-ters up to 2 000 mm and 42 mm for inner diameters above 2 000 mm.An axial distance of at least 250 mm is required for assembling the trans-former sections on the shaft.
Mounting details are not included in the delivery, since they must bedesigned to suit the specific machine. Examples on mounting supports,which can be used in most cases, are showned in Fig. 14.
D INSTALLATION
RARICShaft current protection
1MRK 502 001-UENPage 9
5 SETTING, TESTING AND C
5.1 Setting
5.2 Testing and commission
5.2.1 Injection test
5.2.2 Primary test
6 MAINTENANCE
The setting of the overcurrent relay RXIK 1 is suitably decided afterchecking the magnitude of the stray current to the relay when the genera-tor is running at load. In case of induced stray currents, a setting 50%higher than the setting which gives unwanted operation is recommended.
The time delay set on time relay RXKL 1 should with margin override thetime delay of the phase short-circuit back-up impedance or overcurrentprotection. A normal setting is 3 s.
Set the overcurrent relay and the time relay according to the above. Insertthe RTXH 18 test handle into the RTXP 18 test switch.The primary oper-ating current of the protection is tested by injecting current of rated fre-quency into test winding A - B of the shaft current transformer from testterminals 3B - 4B on the handle. The test winding has four turns, hencethe primary operate shaft current is four times the injected operate current.Observe that for RARIC Version 2, rated frequency is 150 or 180 Hz. Forthis version, the relay shall not operate at lowest setting when 3 V ratedfrequency voltage is applied to relay terminals 107:231 - 241, (see Fig. 4).
Without altering the settings, interchange the leads to the test terminalsand check the operate value. It can be different from the earlier measuredvalue. Both values should be recorded for comparison at future tests.
Set the injection current to 2 times the operate value and check the timedelay.
Connect a brush via a test lead to an ammeter and then further to groundvia a series connected adjustable resistor, 0 - 30 ohms. When the machineis running, press the brush against the shaft near the insulated bearing andreduce the resistance until the relay operates. Record the operate current.
Check the external connections for the trip and alarm signals.
Under normal conditions RARIC requires no special maintenance.The covers should be installed in place and the hole for the current settingknob should be blanked off with a plastic plug.
Maintenance testing at regular intervals, say every second years, should bemade. The testing is suitably made by injection of current to the test wind-ing, since this also checks the ILDD transformer and the wiring up to theprotection.
OMMISSIONING
ing
1MRK 502 001-UENPage 10
RARICShaft current protection
7 TECHNICAL DATA
Table 1: Basic dataCurrent setting range (RXIK) 0.5-2 mA, 50-60 HzOperate shaft current at setting0.5 mA and transformer diameters160-3000 mm
Version 1: 0.4-1.0 A, 50-60 HzVersion 2: 0.4-1.0 A, 150 Hz
Reset ratio > 99%
Filter characteristic, version 2 The filter rejects the fundamental by 70:1
Input impedance 80 ohm resistive
Overload capacityshaft diameter < 700 mmshaft diameter 700-1600 mmshaft diameter 1610-2500 mmshaft diameter > 2500 mm
50 A shaft current continuously and 200 A in 1 s65 A shaft current continuously and 250 A in 1 s75 A shaft current continuously and 300 A in 1 s100 A shaft current continuously and 400 A in 1 s
Auxiliary rated voltage 100, 110 and 220 V, 50-60 Hz or 24-250 V DC
Power consumption from aux.voltageAC supplyDC supply
Approx. 2 VA before and 8 VA after operation Approx. 3 W before and 7 W after operation
Time setting range (RXKL) 30 ms-99 h
Permissible ambient temperature -5 to +55 °C
Permissible range auxiliary voltage supply
80-110 % of rated voltage
Table 2: Electromagnetic compability tests
Power frequency test (SS 436 15 03) 0,5 kV, class PL4
Fast transient test (SS 436 15 03) 4-8 kV, class PL4
1 MHz burst test (IEC 60255-22-1) 2.5 kV, class III
Table 3: Insulating tests (IEC 60255-5)
Dielectric test 2 kV, 50 Hz, 1 min
Impulse voltage test 5.0 kV, 1.2/50 µs, 0.5 J
Table 4: Contact data
Trip circuits (RXME 18)
Max system voltage within acontact set 450 V dc, 400 V ac
Current-carrying capacity for already closed contact 55 A for 200 ms
30 A for 1 s6 A continuously
Making and conducting capacity,L/R < 10 ms 30 A for 200 ms
20 A for 1 s
Breaking capacity,max. 250 Vac, PF > 0.1 20 A
Breaking capacity, dc, L/R < 40 ms 20 A at 24 V18 A at 48 V3 A at 110 V1 A at 220 V
RARICShaft current protection
1MRK 502 001-UENPage 11
Alarm circuits (RXKL1, RXTUG22H/RXIK1)
Max. system voltage within acontact set 250/250 V dc
250/250 V ac
Current-carrying capacity for already closed contact 30/– A for 200 ms
15/10 A for 1 s5/4 A continuously
Making and conducting capacity,L/R < 10 ms 30/20 A for 200 ms
10/10 A for 1 s
Breaking capacity, dc, L/R < 40 ms 2/1,5 A at 24 V1/0,5 A at 48 V0,4/0,2 A at 110 V0,2/0,1 A at 220 V
Table 5: Weights and dimensions
Weight RARIC , version 1RARIC , version 2
ILDD
4 kg5 kg
10 + 80(D - 300) / 2300 kgwhere D is the inner diameter in mm
DimensionRARIC , version 1RARIC , version 2
ILDD
4U 24C4U 36C
See Fig. 11
Table 4: Contact data
1MRK 502 001-UENPage 12
RARICShaft current protection
8 DIAGRAMS
16A 16B
31321 11
1)
2)
+
3)
+
17A 17B 17
27
10116
26
316
318
317
25
27
26
16
14
15
17
13
11
16
11921 11
Fig. 5 Circuit diagram 7429 010-AD for RARIC, RK 649 101-AD, Ver-sion 1, with AC/DC-converter RXTUB 2
Fig. 6 Circuit diagram 7429 010-BA for RARIC, RK 649 101-BA, Ver-sion 1, with DC/DC-converter RXTUG 22H
7429010-AD
31
18 22
I
2841
21
4B 4A
1A1B
18A
18B
I
U
126 127 128
118116117
11B 11A
10B 10A
9B 9A
12B 12A
24-250V
I
I
+ + -
101
107
113
119
313
RTXP 18
RXTUG 22H
RXIK 1
RXKL 1
RXME 18
1) TRIPPING OF CB:S ETC.
2) ALARM ETC.
24C
4S
-+
3) LOSS OF EL
15
12
107
101
2A2B
113
3B 3A101
101 107 113 119
313
7429010-BA
RARICShaft current protection
1MRK 502 001-UENPage 13
TRIP
AL
Fig. 7 Circuit diagram 7429 010-FC for RARIC, RK 649 101-FC, Ver-sion 2,with AC/DC-converter RXTUB 2.
Fig. 8 Terminal diagram 7429 010-ADA for RARIC, RK 649 101-AD, Version 1.
7429010-FC
S1
S2
A
B
I
PING ETC.
ARM ETC.
+
220V
110V
+ + -
SHAFT CURRENT PROTECTION
100V0V
RARIC
16A
113:25
101
1A 18A
3B101
4B
+ -
4A
3A
101
107:16
2A 319:
26
17A
107:31
107:41
101
12A
11A
10A
9A 7429 010-ADA
1MRK 502 001-UENPage 14
RARICShaft current protection
TRIPPING ETC.
ALARM ETC.
LOSS OF EL
TRIPPING ETC.
ALARM ETC.
Fig. 9 Terminal diagram 7429 010-BAA for RARIC, RK 649 101-BA, Version 1
Fig. 10 Terminal diagram 7429 010-FCA for RARIC, RK 649 101-FC, Version 2
S1
S2
A
B
I
++ + + + - -
24-250V
SHAFT CURRENT PROTECTION
RARIC
16A
119:25
107:316
107:31810
7:31
7
101
1A 18A
107:
116
107:
118
3B101
4B
+ -
4A
3A
101
113:16
2A 313:
26
17A
113:31
113:41
101
U<
7429 010-BAA
S1
S2
A
B
+
220V
110V
+ + -
100V0V
RARIC
16A
125:25
101
1A 18A
3B101
4B
+ -
4A
3A
101
119:16
2A 331:
26
17A
107:231
107:241
101
12A
11A
10A
9A
I
7429 010-FCA
I
SHAFT CURRENT PROTECTION
RARICShaft current protection
1MRK 502 001-UENPage 15
9 DIMENSION ILDD
Fig. 11 Dimensions of the shaft current transformer ILDD. The measur-ing windings of the two halves are interconnected via the termi-nals S. All dimensions are in mm.
Transformer with D ≤ 2000 mm has the cross-section dimensions accord-ing to Alt. 1.
Transformer with D > 2000 mm is split up in four parts and has the cross-section according to Alt. 2.
Max
70
38
50
Alt. 1
42
65
Max
85
Alt. 2
D±5
AQ Trafo AB B
A
S2S1S
en02000669.vsd
S
1MRK 502 001-UENPage 16
RARICShaft current protection
10 MOUNTING
Fig. 12 Recommended mounting of the shaft current transformer ILDD on hydro generators
Fig. 13 Recommended mounting of the shaft current transformer ILDD on turbo generators
RARIC
Oil film
Bearing housing
Insulation
Rotor
Turbine
Shaft current transformer ILDD
en03000001.vsd
RARIC
GeneratorTurbine
Earthing
Shaft current transformer ILDD
Insulation
Bearing
Oil film
Bearing
en03000002.vsd
RARICShaft current protection
1MRK 502 001-UENPage 17
The transformer should be mounted with 4 supports. One of the alterna-tives 1, 2 or 3 can normally be used. Except the supporting bar all detailsare the same for all alternatives. Site weldings indicated for alternative 1applies to all alternatives.
Fig. 14 Examples of mounting supports.
en03000004.tif