SIEMENS Generator and Transformer Protection, Synchronizing and Measuring-Metering System


The task of the electrical unit protection is to detect electrical failures and inadmissible operation of the generator, generator bus bar, excitation system, generator transformer and other existence transformer(Station transformer, unit auxiliary transformer) and disconnect faulty circuits with speed and certainly without interference healthy circuits. The mechanical turbine and generator protection is independent from the electrical protection. The generator protection and synchronizing cubicles will be delivered in fully wired and tested cubicles, ready for connection.

Each sub case contains a complete protection device with DC/DC converter for power supply, Potential and current transformers, A/D converter, computer chips, watch dog circuit and trip relays.

An automatic synchronizing unit is furnished for connecting the generator unit to the grid via the generator circuit breaker. It is also possible to connect via the circuit breakers in HV substation if the generator circuit breaker is already closed.

The universal transducers allow measurement of all electrical quantities occurring in any network in a single unit. Especially in power plants and substations transducers are used for isolation of electrical signals and for further processing of measured values.

Combined meters in which is provided for power metering on generator output and for power metering on unit auxiliary transformer.


  • Numerical protection system (NPS) shall mean the protection terminals wherein the analog to digital conversion of the input variables takes place immediately after the input transformers and all further processing of the resulting numerical signals shall be performed by microprocessors and controlled by programs. NPS shall include all features of conventional relays, protective devices, relay panels for generator, generator transformer, unit transformer and station transformer


  • Synchronizing system mean, indicators and control devices required to ensure that, before electrical systems are paralleled, voltages, frequency (speed) and phase angle are equal and in each phase

Measuring and metering:

  • The term measuring mean indicator meters digital type installed in unit local panel and remote monitored in control system.

 Technical Specification :

  • Protection be applicable at different generator types and power plants
  • (Primary Nominal Current from 1kA up to 100kA, Primary Nominal Voltage from 1kV up to 1200kV and Powersystem Apparent Power from 0.2 MVA up to 5000MVA)
  • Synchronizing be applicable at different Single line of power plants and Substations
  • (Primary Nominal Voltage from 0.1 kV up to 1000kV)
  • The implemented functions fulfil the protection requirements for direct connection and unit connection schemes
  • With the combination of 7UM62, 7UT61, 7UT 63 as well as 7SJ6 flexible redundancy concepts are feasible in protection
  • Direct read out from the relays and stored on a disk(*.zip file).
  • Operating program DIGSI4 with online help
  • Acquisition of all relevant measured values
  • Storage of events in buffers (disturbance recording, event log and trip log buffers)
  • Flexible tripping concepts (Tripping matrix, lockout or master relay tripping)
  • Disturbance recorder with instantaneous or rms values (calculated values, every cycle; length max. 80 s)
  • The communication with control systems is realized with Profibus DP (annunciations and measurements)
  • Browser operation
  • The devices adjustment can be done by using integrated LC‑Display and keypad or, very comfortably, by using a PC and the DIGSI‑Software.
  • All specific data are stored in EEPROM circuits in which the information is kept also if the device is switched off. (Batteries are not necessary.)
  • Insensitive to VT and CT errors, transient conditions and interferences.
  • In Synchrozing relay,High reliability of the CLOSE command forming through the TWO out of TWO decision
  • 1/2- channel design at the 7VE61 (Sync-check + Paralleling function)
  • 2-channel design at the 7VE63 (two different paralleling principles)
  • Consideration of the transformer vector group and the position of the tap changer
  • Balancing commands for voltage and speed (frequency)
  • Synchronisation record (instantaneous or rms)
  • Syncron Commissioning support (CB-time measurement with recorder function, test synchronisation)
  • The reliability of synchron relay will be increased with additional supervision principles
  • Measuring system, using Transducers
  • measurement of all electrical quantities in a single unit
  • All data freely parameterizable
  • The output signal is for e.g. -10 to 0 to 10 mA,± 20 mA, 4 to 20 A, 0 to 10 V, etc.
  • Accuracy Acc. to IEC 60688
  • Metering system, using Landis & Gyr Energy Meters
  • Retransmission contacts :No, 4 changeover or 8 make contacts
  • Quadrant splitting (4 quadrant measurement)
  • Reactive energy in class 1 possible (cl. 2 performed by IEC)
  • Active energy in class 0.2S possible(cl. 0.5S performed by IEC)
  • Standard protocols for communication
  • More measurement quantities like single phases, U, I, VA
  • Excellent measurement behaviour (both energy directions)


Features :

  •  Two redundant auxiliary DC supply circuit
  •  Standard features of numerical relays
  •  International protection standards (IEC, ANSI)
  •  Hardware and software based on SIPROTEC 4
  •  Time Synchronization with GPS or other systems
  •  Userfriendly Softwre
  •  Extension and new combination of functions
  •  Self supervision of hardware and software
  •  High sensitivity and a wide frequency operating range of protection & Synchronizing     functions
  •  Communication interfaces
  •  User-defined Functions is possible
  •  Insensitive to VT and CT errors, transient conditions and interferences
  •  Setting examples (manual or online help)
  •  All implemented protection functions run in parallel without limitations (functionality depends on the connection)
  •  Variety of generator synchron modes
  •  Synchronizing in local and remote control panels are available
  •  All relays are maintenance free
  •  Automatic synchronisation of generators
  •  Synchrocheck at manual synchronisation of generators
  •  Switching of dead busbar or dead line
  •  Clear and comprehensible documents
  •  Simple and secure commissioning
  •  Commissioning support
  •  High precision measuring-metering system
  • All requirements for measuring-metering system guaranteed according to IEC 62053-22 (former 60687)