Siemens 7UT51

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7UT51 v3

Application Examples

PRIM-2330C 37

Figure 3.10

Differential Protection for Radial Distribution Transformer and Bus Configuration, Feeder Breakers Excluded

Figure 3.11

Differential Protection for Radial Distribution Transformer and Bus Configuration, Feeder Breakers Included

Main Page

Table of Contents3
Introduction11
Using this Manual11
Definitions of Terms11
Description of Relay13
Overview13
Features13
Protection Overview13
Differential Protection (87T/87HS, 87M/G, 87B)14
Overcurrent Protection (50/51, 50HS)14
Thermal Overload Protection (49-1, 49-2)15
Ground Differential Protection (87N)15
Tank Leakage Protection (64T)15
Metering15
Commissioning Data16
Data Acquisition16
Configuration & Analysis Software (Windigsi )16
Data Communication Ports16
Control16
Construction17
Catalog Number17
Protection Functions Available at 60Hz18
Inputs and Outputs18
Phase Differential Protection of a Transformer (87T and 87HS)20
Phase Differential Protection of a Transformer (87T and 87HS)21
Phase Differential Protection of a Generator or Motor (87G/M)22
Phase Differential Protection of a Bus (87B)23
Ground Differential Protection (87N) (Optional with 7UT513)24
Overcurrent Protection (50/51 and 50HS)25
Thermal Overload Protection (49-1 and 49-2)26
Tank Leakage Protection (64T)27
Service, Storage, and Transport Conditions27
Application Examples31
Transformer Protection31
Reactor Protection33
Motor and Generator Protection34
Bus Protection35
Transformer Differential Protection (87T and 87HS)39
Method of Operation39
Matching Currents39
Handling Non-Ideal Behavior41
Describing the Transformer43
Type of Transformer44
Normal Operational Status44
System Frequency44
Rated Phase-To-Phase Voltage45
Rated Apparent Power45
Phase Shift between Windings45
Describing the CT Scheme48
Nominal Secondary Rating of Cts48
Nominal Primary Rating of Cts48
Three-Winding Transformers with Considerably Different Rated Powers48
Orientation of Cts49
Processing the Zero Sequence Current49
Zero-Sequence Current Elimination Vs. Correction Mathematical Illustration50
Using a Ground or Neutral Current CT54
Trip Characteristic55
Minimum 87T Trip Threshold56
High Set (87HS) Trip Threshold56
Lower Slope of Pickup Characteristic57
Upper Slope of Pickup Characteristic58
Through-Fault Restraint58
Second-Harmonic Restraint59
Higher-Harmonic Restraint60
Blocking by Frequency Variance61
Time Delays61
Events and Actions62
Single-Phase Transformers66
Motor or Generator Differential Protection (87M/G)67
Method of Operation67
Describing the Protected Motor or Generator67
Type of Protected Object68
Normal Operational Status68
System Frequency68
Motor/Generator Information68
Describing the CT Scheme69
CT Orientation69
Nominal Primary Rating of Cts71
Nominal Secondary Rating of Cts71
Trip Characteristic71
Trip Characteristic Settings72
Through-Fault Restraint74
Blocking by Frequency Variance74
Time Delays75
Events and Actions75
Bus Differential Protection (87B)79
Method of Operation79
Describing the Protected Bus79
Type of Protected Object79
System Frequency80
Rated Nominal Current80
Normal Operational Status80
Describing the CT Scheme81
Nominal Primary Rating of Cts81
Nominal Secondary Rating of Cts81
Orientation of Cts81
Trip Characteristic83
Trip Characteristic Settings84
Through-Fault Restraint85
CT Circuit Monitoring86
Time Delays86
Events and Actions86
Ground Differential Protection (87N)91
Calculated Quantities92
Trip Decision93
Second Harmonic Restraint94
Normal Operational Status95
Pickup Level and Limit Angle95
Harmonic Restraint96
Time Delays96
Events and Actions96
Time Overcurrent Protection (50HS and 50/51)99
Method of Operation99
Normal Operational Status99
High-Set Element (50HS)100
Overcurrent Element (50 or 51)100
Definite Time Element (50)101
Inverse Time Element (51)101
Reset Time Delay101
Overcurrent Protection During Manual Close of Breaker102
Events and Actions106
Thermal Overload Protection (49-1, 49-2)107
Method of Operation107
Normal Operational Status108
Pickup Characteristic and Warning Levels108
Maximum Continuous Overload Current108
Time Constant Τ108
Warning Alarm Levels109
Temperature Rise Calculation Method109
Logical Events and Actions111
Tank Leakage Protection (64T)113
Method of Operation113
Normal Operational Status113
Pickup and Dropout Levels114
Time Delays115
Events and Actions115
Protecting an Additional Device or Equipment117
Protection Self-Monitoring119
Self-Monitor Signal Contact119
Internal Self-Monitoring119
Reset of Leds119
Change of Parameter Set119
Software-Hardware Mismatch119
Data Buffer Invalid or Overflowing119
Memory Monitoring (Checksum)119
Processor120
Internal Power Supplies120
Analog/Digital Converters120
Trip Circuits120
Monitoring of Supply Power120
Monitoring of CT Circuits120
Current Symmetry120
Current Summation121
Events and Actions122
Binary-Signal Inputs, Signal Contacts, Trip Contacts, and LED Indicators123
Overview123
Binary-Signal Inputs126
Signal Output Contacts127
Programmable Signal Contacts127
LED Targets128
Trip (Command) Contacts129
Processing External Trip Commands131
Normal Operational Status131
Time Delays131
Numerical Listing of User Definable Trip and Signal Functions132
Operation Using the Front Panel Controls137
Front Panel Components137
Display137
Keypad137
On/Off Switch137
Relay Nameplate138
LED Indicators139
Custom LED Labels140
Data Communications Port140
Viewing a Setting140
Entering an Address Directly140
Scrolling to an Address141
Changing a Setting141
Entering Password Mode141
Changing an Entered Value142
Changing a Setting Selected from a List142
Changing a Control Configuration Option142
Using Multiple Settings Groups143
Selecting Which Group to Configure143
Changing the Group in Use by the Relay143
Copying a Group's Contents144
Operational/Event Log and Fault Logs145
Viewing a Log145
Clearing a Log146
Measured Values146
Capturing Waveform Data147
Address Blocks149
General Configuration151
Front-Panel Display Options151
Use of Multiple Parameter Sets151
Setting Date & Time152
Operation Using a Personal Computer153
Overview153
Programming the Relay154
Parameter Menu154
Configuration Menu154
Marshalling Menu156
Settings Menu Example for Transformer Protection156
Bench Testing159
Required Test Equipment159
Important Notes for this Procedure160
Annunciations and Setting Examples160
Verify Actual Programming of Trip Relays and Signal Relays160
Control of Protective Elements by Discrete Inputs During Testing160
Testing Transformer Differential Protection160
Ideal Through-Fault Test162
Validate Metering163
Three-Winding Transformer Differential Protection (7UT513 Only)164
Testing the Differential Element 87T165
Testing Differential Setting of High-Set Element 87HS166
Testing Harmonic Restraint167
Testing Restricted Ground Fault Protection (7UT513 Only)167
Branch Point Differential Protection Testing171
Backup Overcurrent Time Protection Testing171
Testing the High-Set Overcurrent Stage172
Testing the Definite Time Overcurrent Stage172
Testing the Inverse Time Overcurrent Stage172
Thermal Overload Protection Testing173
Warning, Overload Current: Address 2405 (49-1) and 2505 (49-2)174
Warning, Temperature: Addresses 2404, 2403 and 2402175
Addresses 2504, 2503, and 2502 (49-2)175
Tripping: Addresses 2402 and 2403 (49-1), 2502 and 2503 (49-2)176
Tank Leakage Protection Testing (if Available)177
External Trip Function Coupling Testing177
Putting the Relay into Operation178
Installation and Servicing179
Transport and Storage179
Unpacking and Repacking179
Removing and Inserting the Relay Modules180
Mounting the Relay Case181
Wiring183
Connection Diagrams184
Checking Connections188
Replacing the Internal Fuse188
Installing or Replacing the Battery189
Changing the Rated Nominal Current of the Current Inputs189
Changing the Rated Voltage of the Binary-Signal Inputs192
Changing the Normal Signal Position of the Fiberoptic Data Port194
Field Testing and Commissioning195
Preparation195
Physical Inspection195
Energizing the Relay196
Check Matching Factors197
Preparation of Primary Tests197
Symmetrical Current Tests, Address Block 4100198
Tests Related to All Applications199
Tests Related to Protected Objects with Three Terminals201
Preparation for Zero Sequence Current Tests202
Zero Sequence Tests - Address Block 4100202
Current Test for Restricted Ground Fault Protection, Address Block 41203
Leaving Test Operation, Address Block 4800205
Checking the Coupling of External Trip Signals205
Operational Checks205
Energizing the Protected Object206
In-Service Readings206
Operational Measured Values206
Measured Current Tests - Address Block 4100206
Waveform Capture During Test Fault Record - Address 4900207
Installation of 7UT51 Relay in Existing Circuit208
Output Connections208
Testing for In-Service Setting Changes208
Putting the Relay into Operation209
Maintenance and Servicing211
Troubleshooting Tips211
Routine Checks211
When to Return a Relay212
Settings Record213

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