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⎯

6 F 2 S 0 7 5 8

Fuse

GRD140

Figure 2.1.7

Feeder Protection Coordinated with Fuses

Configuring the inverse time element OC1 (and EF1) and time graded elements OC2 and OC3 (or
EF2 and EF3) as shown in Figure 2.1.8, the characteristic of overcurrent protection can be
improved to coordinate with the fuse characteristic.

Current (amps)

Time (s)

OC2

OC3

Fuse

OC1

Figure 2.1.8

Staged Definite Time Protection

Summary of Contents for GRD140

Page 2: ... be followed by important safety information that must be carefully reviewed Indicates an imminently hazardous situation which will result in death or serious injury if you do not follow the instructions Indicates a potentially hazardous situation which could result in death or serious injury if you do not follow the instructions CAUTION Indicates a potentially hazardous situation which if not avo...

Page 3: ...ION Earth The earthing terminal of the equipment must be securely earthed CAUTION Operating environment The equipment must only used within the range of ambient temperature humidity and dust detailed in the specification and in an environment free of abnormal vibration Ratings Before applying AC voltage and current or the DC power supply to the equipment check that they conform to the equipment ra...

Page 4: ...anner according to local regulations 环保使用期限标识是根据电子信息产品污染控制管理办法以及电子信息产品污染控制标识要求 SJ T11364 2006 电子信息产品环保使用期限通则制定的适用于中国境内销售的电子信息产品的标识只要按照安全及使用说明内容在正常使用电子信息产品情况下从生产日期算起在此期限内产品中含有的有毒有害物质不致发生外泄或突变不致对环境造成严重污染或对其人身财产造成严重损害产品正常使用后要废弃在环保使用年限内或者刚到年限的产品请根据国家标准采取适当的方法进行处置另外此期限不同于质量功能的保证期限 The Mark and Information are applicable for People s Republic of China only ...

Page 5: ...n 63 2 2 3 Zero Phase Sequence Overvoltage Protection 66 2 2 4 Negative Phase Sequence Overvoltage Protection 69 2 3 Frequency Protection 71 2 4 Trip and Alarm Signal Output 73 2 5 Autoreclose 75 2 5 1 Scheme Logic 75 2 5 2 Sequence Coordination 76 2 5 3 Setting 77 3 Technical Description 80 3 1 Hardware Description 80 3 1 1 Outline of Hardware Modules 80 3 2 Input and Output Signals 84 3 2 1 AC I...

Page 6: ...g Records 115 4 2 4 Displaying the Status 120 4 2 5 Viewing the Settings 126 4 2 6 Changing the Settings 127 4 2 7 Testing 170 4 3 Personal Computer Interface 173 4 4 Relay Setting and Monitoring System 173 4 5 IEC 60870 5 103 Interface 174 4 6 Clock Function 174 5 Installation 175 5 1 Receipt of Relays 175 5 2 Relay Mounting 175 5 3 Electrostatic Discharge 175 5 4 Handling Precautions 175 5 5 Ext...

Page 7: ...nd Recording 195 6 6 Conjunctive Tests 196 6 6 1 On Load Test 196 6 6 2 Tripping and Reclosing Circuit Test 197 6 7 Maintenance 199 6 7 1 Regular Testing 199 6 7 2 Failure Tracing and Repair 199 6 7 3 Replacing Failed Relay Unit 200 6 7 4 Resumption of Service 201 6 7 5 Storage 201 7 Putting Relay into Service 202 ...

Page 8: ... Menu and LCD Button Operation 225 Appendix F Case Outline 241 Appendix G Typical External Connection 243 Appendix H Relay Setting Sheet 249 Appendix I Commissioning Test Sheet sample 263 Appendix J Return Repair Form 267 Appendix K Technical Data 271 Appendix L Symbols Used in Scheme Logic 279 Appendix M IEC60870 5 103 Interoperability 283 Appendix N Inverse Time Characteristics 291 Appendix O Or...

Page 9: ...t three phase auto reclose with independent sequences for phase fault and earth fault and sensitive earth fault Auto reclosing can also be triggered by external protection devices Other protection functions are available according to model type including thermal protection to IEC60255 8 negative sequence overcurrent protection under overvoltage and under overfrequency protections See Table 1 1 1 f...

Page 10: ...Negative Phase Sequence Overvoltage NOV1 NOV2 47 9 9 Under Overfrequency FRQ1 FRQ4 81U 81O 9 9 Broken Conductor BCD 9 9 Circuit Breaker Fail CBF 50BF 9 9 Cold Load Protection 9 9 Auto reclose 79 9 9 9 Fault Locator 9 9 CT Supervision 9 9 VT Supervision 9 9 Trip circuit supervision 9 9 9 Self supervision 9 9 9 CB State Monitoring 9 9 9 Trip Counter Alarm 9 9 9 Iy Alarm 9 9 CB Operate Time Alarm 9 9...

Page 11: ...nges in the power source impedance it is advantageous to use inverse definite minimum time IDMT overcurrent protection This protection provides reasonably fast tripping even at a terminal close to the power source where the most severe faults can occur Where ZS the impedance between the relay and the power source is small compared with that of the protected section ZL there is an appreciable diffe...

Page 12: ...ed for each IDMT element by scheme switch M C Table 2 1 1 Specification of IDMT Curves Curve Description k a c kr b IEC Normal Inverse NI 0 14 0 02 0 IEC Very Inverse VI 13 5 1 0 IEC Extremely Inverse EI 80 2 0 UK Long Time Inverse LTI 120 1 0 IEEE Moderately Inverse MI 0 0515 0 02 0 114 4 85 2 IEEE Very Inverse VI 19 61 2 0 491 21 6 2 IEEE Extremely Inverse EI 28 2 2 0 1217 29 1 2 US CO8 Inverse ...

Page 13: ... Figure 2 1 3 IDMT Characteristics Programmable Reset Characteristics OC1 EF1 and SEF1 have a programmable reset feature instantaneous definite time delayed or dependent time delayed reset Refer to Appendix A for a more detailed description Instantaneous resetting is normally applied in multi shot auto reclosing schemes to ensure correct grading between relays at various points in the scheme The i...

Page 14: ...he energising current falls below the reset threshold the integral state the point towards operation that it has travelled of the timing function IDMT is held for that period This does not apply following a trip operation in which case resetting is always instantaneous Dependent time reset The dependent time resetting characteristic is applied only to the IEEE US operate characteristics and is def...

Page 15: ...ection is applied The operating time can be constant irrespective of the magnitude of the fault current The definite time overcurrent protection consists of instantaneous overcurrent measuring elements and delayed pick up timers started by the elements and provides selective protection with graded setting of the delayed pick up timers Thus the constant time coordination with the downstream section...

Page 16: ...ffective particularly for feeders near the power source where the setting is feasible but the longest tripping times would otherwise have to be accepted As long as the associated inverse time overcurrent protection is correctly coordinated the instantaneous protection does not require setting coordination with the downstream section Figure 2 1 6 shows operating times for instantaneous overcurrent ...

Page 17: ...the inverse time element OC1 and EF1 and time graded elements OC2 and OC3 or EF2 and EF3 as shown in Figure 2 1 8 the characteristic of overcurrent protection can be improved to coordinate with the fuse characteristic Current amps Time s OC2 OC3 Fuse OC1 Figure 2 1 8 Staged Definite Time Protection ...

Page 18: ...rrows The various overcurrent elements of GRD140 are independently programmable for directional operation Therefore elements OC2 and EF2 could be set for non directional operation to provide time delayed back up protection for the load F GRD140 GRD140 GRD140 GRD140 Load A B Directional Directional Non directional Non directional Figure 2 1 9 Application of GRD140 to Parallel Feeders Ring Main Circ...

Page 19: ...at both line terminals as shown in Figure 2 1 11 the fault current flows in from both terminals c b a 1 2 3 G1 G2 F2 F1 Figure 2 1 11 Protection of a power system with sources at both line terminals The protection is performed by setting the directional element at points 1 2 and 3 which operates only when the fault current F1 solid lines flows in from source G1 and at points a b and c which operat...

Page 20: ...Figure 2 1 13 Directional element Polarising signals of directional elements are shown in Figure 2 1 14 Polarisation for directional phase overcurrent element OC is achieved by the 90 quadrature method whereby each current s phase angle is compared with the phase to phase voltage between the other two phases Since the voltage inputs to the relay will normally be connected phase to neutral the pola...

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