Dec 3, 2015

New Generator Protection Relay


iemens 7UM85

Waiting is finally over. A few days ago, Siemens, now finally and after several years of development, has released the new 7UM85 machine protection relay. The device is the consequent further development of the 7UM6x of the V4 generation. It is also specially designed for the protection of generators and power units. Contrary to the predecessor version, the new 7UM85 is modular and accordingly flexible. The basic function with hardware standard variant starts at 3,400 EUR and then goes according to the equipment accordingly upwards. DIGSI5 is expected to be a powerful engineering tool. For the first time, all functions can be freely configured and combined. The following functions are available to the user:

- Short-circuit protection (overcurrent protection, impedance protection, differential protection)

- Stator ground fault protection (90% non-directional or directional; 100% with 3rd Harmonic, real 100% protection with 20 Hz voltage injection)

- Rotor ground fault protection with various measuring methods (earth current and earth resistance monitoring)

- High-precision reverse-power protection and universal power protection

- Underexcitation and overexcitation protection

- Unbalanced load protection

- Overload protection up to the 50th harmonic and temperature monitoring via Thermo box (e.g. with PT 100)

- Out-of-step protection

- Shaft current protection (especially in hydropower applications)

- Universal overvoltage and undervoltage protection with various measuring methods

- Over- and underfrequency protection and rate of change of frequency protection

- Protection functions for grid decoupling (voltage/ frequency protection and reactive power direction undervoltage protection (QU protection)

- Additional protection for detecting faulty closing of the circuit breaker

- Circuit-breaker failure protection

- Circuit-breaker restrike protection

- Graphic logic editor for creating powerful automation functions in the device.

- Integrated electrical Ethernet port J for DIGSI and IEC 61850 Reporting

- Optional pluggable communication modules usable for different and redundant protocols (IEC 61850, IEC 60870-5-103, IEC 60870-5-104, Modbus TCP, DNP3 (serial and TCP))

- Secure serial protection data communication, also over great distances, and all available physical media (e.g. fiber optic cable, wire connections and communication networks)

- High-availability redundancy protocols PRP and HSR

- Cyber security in accordance with NERC CIP and BDEW Whitepaper

- Phasor Measurement Unit (PMU) for synchrophasor-measured values and IEEE C37.118 protocol

- Time synchronization with IEEE 1588

- Acquisition of operational measurands and protection function measured values for assessing the system status and supporting commissioning and fault clarification

- Powerful fault recording (buffer for max. recording time 80 s at 8 kHz or 320 s at 2 kHz sampling frequency)

- Help functions for simple tests and easy commissioning

- Flexibly adjustable I/O quantity structure within the scope of the SIPROTEC 5 modular system

What first comes to mind is the new "circuit-breaker restrike protection" function. As soon as the manual for the 7UM85 is available, we will inform you how the function works and in which way we will consider this it in the future. There is currently no practical experience with the new device.

We'll get back to you as soon as we have the first experiences with this device. Nice that Siemens managed the Christmas business, since we all hope for the 7UM85 under the Christmas tree ;-)

Greetings Alexander Muth

(Source: Siemens SIPROTEC)

PS .: The proper way of commissioning generator protection systems: You will learn everything you need to know in my new book: "The Bible of Generator Protection Engineering - The commissioning manual for professionals"