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Testing firmly under control: Simplified protection tests with FAME at EnergieNetz Mitte


Grid monitoring  

Markus Hose from EnergieNetz Mitte actuates a FAME plug

  • EnergieNetz Mitte, a subsidiary of the EAM Group, operates approximately 50,000 kilometers of electricity and natural gas grids as well as 71 substations.
  • The grids must be monitored with ever greater precision, and monitoring needs to be easier and safer.
  • Using the FAME plug-in test system from Phoenix Contact, utility company EnergieNetz Mitte is able to achieve high flexibility with increased safety and operating convenience.
  • A significant advantage over earlier solutions: the protective function remains active even during testing.

Customer profile


EnergieNetz Mitte substation © EAM Energie GmbH

For more than 80 years, the EAM Group has been providing a safe and reliable energy supply to around 1.4 million people in Central Germany. Subsidiary EnergieNetz Mitte operates a total of approximately 50,000 kilometers of electricity and natural gas grids as well as 71 substations.


Test procedures  

With FAME, complete test procedures can be integrated in a single connection step

Fast fault detection is a prerequisite for safe and reliable operation of the power grid. To this end, certain variables such as current and voltage are constantly monitored. Digital grid protection relays are used for monitoring – they are responsible for disconnecting and switching over faulty cables or transformers. When a grid protection relay identifies a fault on a supply cable, the circuit breaker for this cable receives a tripping signal and the cable is disconnected.

The proper function of the grid protection relays is tested regularly as part of a protection test program. EAM uses a plug-in contact version for this. After establishing the connection, the measuring transducers are first short circuited via a rotary switch, and the “Circuit breaker OFF” signal is then interrupted. The actual function test can only begin once this step has been completed. Since only one protective device is normally installed on the medium-voltage side, all protective functions are disabled for the duration of the test.


To make it easier and safer to perform protection tests, Phoenix Contact has developed the FAME plug-in test system. This system connects a large number of necessary contacts to the test device in a single connection step. There is no longer any need to actuate a switch – all switching operations are forcibly actuated by plugging in the test plug. The sequence for contacting, disconnecting, and short circuiting the measuring transducers is defined by the plug, and is therefore always correct.

In contrast to actuating a switch, 100% contact overlap is ensured at all times. Safety can be increased even further by using pre-assembled test plugs. Permanently connected test cables that are fitted with a system connector for the test device make the individual connection of the measurement cables superfluous. This eliminates further possible sources of error and speeds up the protection testing process.

“A major reason for switching over to FAME is the rapidly increasing complexity of the systems, which inevitably leads to more complex protection testing,” explains Markus Hose, who is responsible for protection testing in the substations at EnergieNetz Mitte. The test switches that were previously selected are no longer up to date. With contacts for only three currents and three voltages each, and just one OFF signal, they no longer meet today's technical requirements. “In contrast to this, the entire system or all protective systems can now be tested with one FAME plug, which only needs to be configured once,” explains Hose. He therefore plans to equip all new systems with FAME as well.

Using FAME, testing can also be carried out safely and easily in systems that cannot be disconnected. With the test plug, a reserve protective device can be looped in during testing. This ensures that mains protection is maintained even during the protection test.


FAME plug  

The patented rotary handle mechanism ensures precise signal states

This special function for continuous mains safety is also used when a protective device fails; an employee quickly and easily loops in an interim protective device via the FAME plug. If a protective device fails or causes a fault, a service technician (who does not have to be a trained protection engineer) can replace the protective device via the FAME plug, even outside of normal working hours. Faults are therefore quickly eliminated and grid disturbances minimized. The next day, a protection engineer can replace the defective device without affecting the grid.


Unit 15C, 906-930 Great South Road, Penrose
Auckland 1061
New Zealand

Phone: 0508 474 636
Toll Free (Local)
09 950 8495

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