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Limited. No part of this document shall be reproduced or modified or stored in another form, in any data retrieval system, without the permission of Siemens Protection Devices Limited, nor shall any model or article be reproduced from this document unless Siemens Protection Devices Limited consent.
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Limited. No part of this document shall be reproduced or modified or stored in another form, in any data retrieval system, without the permission of Siemens Protection Devices Limited, nor shall any model or article be reproduced from this document unless Siemens Protection Devices Limited consent.
7SG164 Ohmega 400 Series Description of Operation 1 General The relays provide high speed Distance protection and have independent measuring elements for each fault condition and zone of operation. This gives a true full scheme operation. The impedance measurement is a continuous process therefore under impedance starting elements are not required.
7SG164 Ohmega 400 Series Description of Operation 5 Multiple Setting Groups The relays provides up to eight alternative settings groups, making it possible to edit one group while the relay protection algorithms operate using another ‘active’ group. The relay can be switched from one group of settings to another to suit alterations in the power system configuration.
7SG164 Ohmega 400 Series Description of Operation The time and date is also displayed. Where appropriate, additional meter displays are available depending upon the functions supplied with the relay. These will be described in the relevant sections. 7 Data Storage Data records are available in three forms, namely fault records, waveform records and event records.
7SG164 Ohmega 400 Series Description of Operation • Change of state of Status Inputs • Change of state of any protection characteristic • Main Trip Other events are available depending upon the features included in the relay -they are described with the relevant feature.
Note that the password validation screen also displays a numerical code. If the password is lost or forgotten, this code can be communicated to Siemens by authorised personnel, and the password can be retrieved. The relay is supplied with the password set to "NONE" which means the feature is de-activated.
7SG164 Ohmega 400 Series Description of Operation 11.3 LED Indications The following indications are provided: Protection Healthy - Green LED. This LED indicates that DC volts have been applied to the relay and that the relay is operating correctly. If a permanent fault is detected by the internal supervision, then this LED will continuously flash.
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7SG164 Ohmega 400 Series Description of Operation CANCEL FAULT FAULT DATA RELAY IDENTIFIER LED TEST DISPLAY SETTINGS INSTRUMENTS FAULT DATA MODE MODE MODE PRIMARY VOLTAGE SYSTEM CONFIG FAULT 1 PRIMARY CURRENT MENU. TO VIEW SECONDARY VOLTAGE FAULT N SECONDARY CURRENT DISTANCE PROTECTION MENU.
7SG164 Ohmega 400 Series Description of Operation A sub-menu is opened by pressing the key when viewing one of the above title screens. The settings within the sub-menu can then be viewed in turn. Leaving a sub-menu, by scrolling either upwards or downwards, causes it to be automatically closed.
7SG164 Ohmega 400 Series Description of Operation 13.1 Internal Construction The design for the internal arrangement of each module has been chosen to provide a high level of EMI screening, using multi-layer PCBs with ground planes, RFI suppression components and earthed metal screens.
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7SG164 Ohmega 400 Series Impedance Functions 1 Distance Protection Functions 1.1 Polarised MHO Characteristic 1.1.1 Cross-Polarised MHO It is fundamental to the requirements of discrimination that distance protection Zone 1 and 2 measuring characteristics for direct tripping are directional since they are required to detect faults in the forward direction only.
7SG164 Ohmega 400 Series Impedance Functions 1.1.2 Offset Mho Characteristic The offset Mho characteristic is shown in figure 2. The characteristic is set with a forward reach, ZF and a reverse reach, ZR. This type characteristic may be selected for Zone 3, and it provides time delayed back-up for faults behind the relaying point.
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7SG164 Ohmega 400 Series Impedance Functions To correctly measure the impedance to the fault point, the correct current and voltage must be applied to the relay. The relay impedance setting is made in terms of the positive sequence impedance to the point of reach which means that the relay setting is the same for all types of fault.
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7SG164 Ohmega 400 Series Impedance Functions This is a convenient factor to use in the phase comparison logic as the actual value of Z0 is not required provided the ratio Z 0 / Z1 and the phase angles of Z0 and Z1 are available. The K0 factor...
7SG164 Ohmega 400 Series Impedance Functions 1.1.4 Zone 3 Shaped Characteristics In circumstances where the zone conditions come within the reach of the Zone 3 Characteristic blinders can be applied to prevent load encroachment (See figure 7a, below). Obviously, this presents no problem for the Quad characteristic, since the reach along the resistive axis can be limited.
7SG164 Ohmega 400 Series Impedance Functions The above figure shows the position of blinders if different values are chosen for SF1 & SF2. 1.1.5 Comparison of Setting with THR Relay In order to ease application of the characteristic, it is recommended that the same ratios of minor to major axis are used as were provided with the THR relay.
7SG164 Ohmega 400 Series Impedance Functions 1.2 Quadrilateral Characteristic In addition to MHO characteristics, some models of the relay have the option of quadrilateral characteristics for earth fault coverage. The quadrilateral characteristic can be set according to resistive coverage, reactive coverage and the line angle. The resistive cut off blinder is set to the same angle as the line angle.
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7SG164 Ohmega 400 Series Impedance Functions Figure 10 Polarised Directional Characteristic As can be seen, the characteristic moves behind the origin for forward faults, and forward of it for reverse faults. In addition, as the SIR level increases (ZS increases relative to Z) the characteristic moves further from the origin.
7SG164 Ohmega 400 Series Impedance Functions 1.2.2 Offset Quadrilateral Characteristic A typical offset quadrilateral characteristic is shown below. This is constructed using forward and reverse resistance characteristics, and forward and reverse reactance characteristics. This would be used for the offset zone 3 characteristic.
7SG164 Ohmega 400 Series Impedance Functions 1.3 Voltage Memory The relay incorporates a voltage memory feature. This ensures directional security under closein three phase fault conditions when there is little or no healthy phase voltage available for cross-polarising. The relay monitors the positive sequence voltage of the system, and under fault conditions it adds a replica of this voltage to the polarising voltage of each comparator, suitable phase-shifted to align it with the ideal polarising voltage.
7SG164 Ohmega 400 Series Impedance Functions 1.6 Power Swing Characteristics 1.6.1 Applications A power swing is the result of a change in angle between two power systems. Each system can be subjected to disturbances such as faults, loss of load, loss of large generation, etc. which in turn, may result in excursions of generator rotor angles.
7SG164 Ohmega 400 Series Impedance Functions 1.6.2 Description of Operation 1.6.2.1. Power Swing Detection. The relay uses 2 zones of protection to detect a power swing condition, defined as the inner and the outer zones. Each of these zones consists of a phase to phase fault comparator applied to the Yellow- Blue phase.
7SG164 Ohmega 400 Series Impedance Functions 1.7 Voltage Transformer Supervision (VTS) 1.7.1 Applications. A protection voltage transformer (V.T.) would normally be connected to the protection relay terminals via a fuse or a miniature circuit breaker. Operation of these would remove the voltage source for one or more phases.
7SG164 Ohmega 400 Series Impedance Functions approximately 2/3 of the minimum operating time of the zone 1 to ensure an adequate time margin for blocking. The inhibit signal is available immediately whereas the alarm signal has a time delay, which can be set from 0-60000ms to prevent nuisance alarms occurring during circuit breaker switching.
7SG164 Ohmega 400 Series Impedance Functions 1.8 Switch On To Fault (SOTF) 1.8.1 Applications The Zone 1 instantaneous elements of the OHMEGA distance protection are directional and rely upon polarisation from either the faulted phase and/or a healthy phase. When closing on to a bolted fault where all three-phase voltages are extremely low, the Zone 1 instantaneous elements may not operate.
7SG164 Ohmega 400 Series Impedance Functions element. A longer time delay is used for the DC SOTF logic (400ms rather than 200ms) because it needs to incorporate the closing time for the circuit breaker, also. The status input ‘Start Aux DC SOTF’ is connected to a CB auxiliary contact to signal CB closing. This function operates similarly to the Manual Close DC SOTF except that the CB aux contact must indicate that the CB is open for the ‘Min Aux DC SOTF Dead Time’...
7SG164 Ohmega 400 Series Impedance Functions 2 Auxilary Functions 2.1 Fault Locator 2.1.1 Applications The fault locator gives the operator an indication of the location of the fault. This information can be presented in three different formats which are a percentage of line length, or the distance in either miles or kilometres.
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“NONE”. Once a password has been set, the relay will display a 10 digit code in the Change Password setting. If the password has been lost then an authorised person should contact a Siemens representative, quoting this 10- digit code. This can be used to obtain the current password.
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7SG164 Ohmega 400 Series Performance Specification Contents 1 Introduction ................................ 3 2 Technical Specification............................3 Rated Current ............................3 Rated voltage ............................3 Rated Frequency............................3 Characteristic Angle ..........................3 Zone impedance settings ......................... 3 Residual Compensation ........................... 3 Zone 4 Settings ............................3 Voltage Memory ............................
7SG164 Ohmega 400 Series Performance Specification Introduction The following document defines the technical and performance specification of the standard features in this series of relays. Optional features are described in the last part of the document. Performance Data to: IEC60255-6, IEC60255-6A and IEC60255-16.
7SG164 Ohmega 400 Series Performance Specification 2.8 Voltage Memory Under fault conditions the relay adds a replica of the positive sequence voltage to the polarising voltage of each comparator. Voltage memory is applied for a maximum of 200ms, after which time the zone 1 and, where fitted, zone 4 comparators will be either inhibited from operating or have their operation latched until the fault is cleared.
7SG164 Ohmega 400 Series Performance Specification Output configuration:- Instantaneous operation/reset Minimum delayed alarm 100ms Delayed alarm/reset 0.1 – 60s 3.3 Switch On To Fault Two arrangements provide instantaneous tripping when switching on to a bolted three-phase fault. D.C. Line check This arrangement is energised from the circuit breaker closing circuit and allows instantaneous zone 3 coverage for a period of 400ms after energising the line.
7SG164 Ohmega 400 Series Performance Specification Optional Features 7.1 Directional Earth Fault Setting Range Polarising Quantity 1V polarising voltage Characteristics: DTL, IEC-NI, IEC-VI, IEC-EI,IEC-LTI, ANSI-MI, ANSI-VI, ANSI-EI. DEF OverCurrent Setting 0.05 x I to 4 x I in steps of 0.05 DEF IDMTL Characteristic setting 0.05 x In - 4 x In in 0.05 steps.
7SG164 Ohmega 400 Series Performance Specification Range 47Hz to 52Hz 57Hz to 62Hz Setting variation ≤ 5% Operating time variation ≤ 5% Harmonic Content Harmonic content of waveforms Frequencies to 550Hz Operating time variation ≤ 5% Auxiliary DC Supply – IEC 60255-11 Allowable superimposed ac component ≤...
7SG164 Ohmega 400 Series Performance Specification 8.6 Departure from reference setting The class index plus an error not exceeding the class index. 8.7 Departure from reference frequency Over the range of 47 – 52 Hz (50Hz nominal) or 57 – 62 Hz (60Hz nominal), the variations in accuracy are the class index plus an error not exceeding the class index.
7SG164 Ohmega 400 Series Performance Specification 240A for 2 sec 625A for 1 cycle (Peak) AC Voltage Inputs 3.5Vn Continuous 8.15 Burdens Current Circuits AC Burden (VA per phase) 1A tap 0.025 2A tap 5A tap 0.625 Voltage Circuits 0.01VA per phase NB.
7SG164 Ohmega 400 Series Performance Specification ≥ 90% Reset/Operate Voltage Ratio Status Input Performance (110V and 220V) Minimum DC current for operation ≥ 90% Reset/Operate Voltage Ratio NB Status operating voltage need not be the same as the main energising voltage. 48/54 volt rated status inputs...
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7SG164 Ohmega 400 Series Performance Specification 20MHz to 1000MHz, 10V/m ≤ 5% Fast Transient – IEC 60255-22-4 Class IV Variation ≤ 3% 4kV 5/50ns 2.5kHz repetitive Vibration (Sinusoidal) –IEC 60255-21-1 Class 1 Variation Vibration response 0.5gn ≤ 5% Vibration endurance 1.0gn...
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7SG164 Ohmega 400 Series Performance Specification Ohmega 400 Series operating time Phase to Earth Faults SIR = 0.1 SIR = 1.0 SIR = 10 SIR = 30 Fault Position % Figure 1 Ohmega 400 Series operating time Phase to Phase Faults SIR = 0.1...
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7SG164 Ohmega 400 Series Communications Interface 1 Introduction The Communication Interface module in the relay incorporates the following ports: An IRIG-B input for time synchronisation A pair of fibre optic ST connectors for transmit and receive communications (port 1). A pair of fibre optic ST connectors as for (2) but intended for transmit and receive communications to a substation SCADA or integrated control system and using IEC 60870-5-103 protocol.
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7SG164 Ohmega 400 Series Communications Interface 2 Connection Specification And Relay Settings This section defines the connection medium as defined by IEC 870-5-103. Appendix A shows some typical communication connections. 2.1 Recommended cable 200μm Plastic Coated Silica (PCS) or 62.5/125μm glass. All cables should be terminated with ST connectors.
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7SG164 Ohmega 400 Series Communications Interface setting (see section 2.6) to allow use of easily available and relatively inexpensive commercial modems has been provided. The downside to this is that the data security will be reduced slightly, and the system will not be compatible with true IEC60870 control systems.
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7SG164 Ohmega 400 Series Applications Contents 1 Introduction ..............................3 2 Current Transformer Requirements........................3 3 Determination of Relay Settings ........................4 Information Required For The Setting Calculations ................4 Distance Protection Settings ........................4 3.2.1 Overall Settings..........................4 3.2.2 Residual Compensation Settings.
7SG164 Ohmega 400 Series Applications 1 Introduction This family of Digital Distance Relays give full scheme protection with independent measurements for every zone and fault loop. Impedance starting elements are not required. Optional features provide a full range of protection functions supplements by control, metering, data storage, fault locator, auto-reclose and fibre optic data communication capabilities.
7SG164 Ohmega 400 Series Applications 3 Determination of Relay Settings 3.1 Information Required For The Setting Calculations To match a distance protection relay to a feeder the following data must be known:- • Positive sequence of the feeder Z ohm/km •...
7SG164 Ohmega 400 Series Applications 3.2.3 Zone 1 Impedance Setting Normal practice is to make the Zone 1 setting equal to 80% of the positive sequence impedance of the protected feeder to allow for the inherent errors in estimating line impedance’s and possible errors in voltage and current transformers.
7SG164 Ohmega 400 Series Applications OHMS OHMS OHMS The Zone 2 reach is obtained by adjusting the impedance setting. ⎡ ⎛ + ⎤ ⎞ ≥ ⎜ ⎟ Zone Setting ⎢ ⎥ ⎝ ⎠ ⎣ ⎦ The Zone 2 Resistance setting for earth fault quad characteristics is set to give an adequate resistive cover to allow for tower footing resistance and arc resistance.
7SG164 Ohmega 400 Series Applications OHM S OHM S 3.2.6 Zone 4 Impedance Setting The Zone 4 setting has an independent impedance range the line angle is the mirror image of the forward angle and is not independently adjustable. The Zone 4 impedance element can be used to directly trip the relay or it can be used with the scheme logic to provide reverse looking fault detection for protection blocking schemes.
7SG164 Ohmega 400 Series Applications APPENDIX A Status Inputs As stated in the “Performance Specification” (section 5 of this manual), status inputs used for protection signalling are high speed devices with operating times of under 5ms. As supplied, all status inputs are of this type.
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As there are no user serviceable parts in any module, there should be no requirement to remove any component parts. If any component parts have been removed or tampered with, then the guarantee will be invalidated. Siemens reserve the right to charge for any subsequent repairs.
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7SG164 Ohmega 400 Series Installation 2104F70040 – 4 off • Nut M4 2103F11040 – 4 off 4.3 Communications ST fibre optic connections – 4 per relay (Refer to section 4 – Communications Interface). 5 Ancillary Equipment The relay can be interrogated locally or remotely by making connection to the fibre optic terminals on the rear of the relay or the RS232 port on the relay fascia.
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7SG164 Ohmega 400 Series Commissioning 1 Commissioning A separate commissioning guide is available for each model of the relay which details the testing of each function. 1.1 Required Test Equipment 1000V Insulation resistance test set. Digitally controlled automatic test equipment suitable for distance relay testing (3 phase o/ps)
LED, or no LED light indicates faulty equipment. As there are no user serviceable components in the withdrawable modules, faulty relays must be returned to Siemens. Using the automatic test equipment, inject 1 amp 3 phase into the current circuits of the relay and apply 63.5 volts 3 phase to the voltage circuits.
7SG164 Ohmega 400 Series Commissioning • Inject at least 50% of the rated primary current into the red phase (figure 1b). Record the ammeter readings in Table 1. Check that:- • Meters A, A1, A4 and relay meter readings Ia and Ix give the same reading.
7SG164 Ohmega 400 Series Commissioning operations occur correctly. If possible, using a P.C. or laptop computer loaded with Reydisp Evolution software, check the current and voltage waveforms and relay operations. For phase-earth faults, check that correct tripping as per scheme is obtained i.e. either single pole tripping or three pole tripping with the associated control operations.
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7SG164 Ohmega 400 Series Maintenance 1 Maintenance Instructions The relay is a maintenance free device, with no user serviceable parts. During the life of the relay it should be checked for operation during the normal maintenance period for the site on which the product is installed. It is...
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7SG164 Ohmega 400 Series Maintenance 2 Trouble Shooting Guide The following table describes the action of the relay under various conditions, and suggested remedial actions when problems are encountered. If problems are being experienced and the suggested action does not work, or the problem is not detailed below, then please contact Siemens.
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7SG164 Ohmega 400 Series Maintenance SYMPTOM PROBLEM ACTION Relay unable to communicate using Communication Ensure connection between PC and relay Reydisp Evolution software channel incorrectly (either via the front RS232 port or TX2 and configured. RX2 on the rear of the relay) has been correctly made.
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7SG164 Ohmega 400 Series Stub Protection 1 Stub Protection The Stub protection function in the relay is used to protect a short section of bus bar when the plant configuration is such that the line V.T. is switched out of circuit. The relay uses an over current element who’s output is gated with a status input.
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Printed in Fürth Printed on elementary chlorine-free bleached paper. All rights reserved. Trademarks mentioned in this document are the property of Siemens AG, its affili- ates, or their respective owners. Subject to change without prior notice. The information in this document contains general descriptions of the technical options available, which may not apply in all cases.
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