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Optimisation of sensors and functional enhancements to devices

In recent years, intelligent powerstations have been increasingly equipped with new features that have been tested in pilot projects for some years by many distribution grid operators. The results have an impact on technology and economic factors that contribute to decision-making for the expansion of smart grids or the distribution grid’s cabling. Against this background, Dipl.-Ing. H. Horstmann GmbH has optimised its products and equipped these with new features.

Bushing-type sensors

We have continued to pursue the idea of installing sensors via the medium voltage load switchgears’ bushing. In the meantime, bushing-type sensors are available for all major switchgear manufacturers. The benefit for new constructions is the integration of current sensors in the switchgear. This saves time and money for switchgear manufacturers, and the subsequent assembly of cable terminations in the field is easier and faster. The new closed bushing-type sensors have the same electrical properties as the split-core sensors already in use and are intended to connect the device series
Compass, Sigma D/D+/P and Sigma F+E 3. These sensors are also suitable for the new product developments from Horstmann planned for 2016.

Wega 1.2 C, Wega 2.2 C, Wega 1.2 C vario

The integrated voltage-detecting system WEGA has been part of the medium-voltage switchgears for years now and is displacing the
HR-/LRM socket modules from the market as it is maintenance-free and self-monitoring. With the new Wega 1.2 C and Wega 2.2 C, according to IEC 61243-5 (VDE 0682-415) one modification per switchgear is required to cover the voltage level 10-24 kV (40.5 kV). This wide-range Wega simplifies storage and can therefore be used with different medium voltage levels.By default, the Wega 1.2 C and Wega 2.2 C have an interface to the short-circuit and earth fault indicators ComPass and Sigma D/D+/P as a reference signal to determine the direction of short-circuits and earth faults, as well as an analogue signal to measure voltage in the
Compass B.

Short-circuit indicator Sigma F+E 3

The Sigma F+E 3  with its split-core  and closed sensors is the short-circuit indicator for all networks. The Sigma F+E 3 with its separate earth fault trip current for detecting earth faults in low-impedance earthing/short-term low-impedance earthing networks allows the phase-selective detection and remote signalling of faults. The Sigma F+E 3i also offers early detection of intermittent earth faults in cables, connectors and sleeves of low-impedance earthing (low-ohmic) networks. This early detection can also be displayed and remotely signalled on-site.

Sigma D/D+: Directional short-circuit and earth fault indicator

The Sigma D/D+ is the directional short-circuit and earth fault indicator for all neutral point treatments. The LED indicators on the front panel clearly indicate the direction of a fault. The capacitive-voltage-detecting system Wega offers a simple interface as a reference signal for the direction feature to determine the direction. The Sigma D/D+ performs the necessary voltage calibration independently without a start-up engineer having to take action. Several positioning procedures are available for finding the position of the earth fault, which enables the fault location of transient and steady state errors to be precisely determined. In addition, the Sigma D/D+ also includes a fault and event memory. The error patterns can be reproduced in this way. The data from the error and event memory can be downloaded via the USB interface. Parametrisation via the USB interface is also possible, which may alternatively also take place via DIP switches.

Compass Bs with integrated remote control unit

The directional short-circuit and earth fault indicator Compass B with a monitoring feature has also been enhanced with the remote distance control feature for load break switches and circuit-breakers. By integrating the remote control feature in the medium voltage switchgear’s control field, information can be queried from the individual fields and switching commands can be sent to the switch. Only the auxiliary voltage and communication cables must be connected to the system. The switch fields can be standardised with this set-up.
A design for each station with different configurations and an additional control field is thus omitted. Another advantage of this set-up is to monitor the load-break switch’s maximum apparent and blind currents. These can cause a breakdown in the switch-off process if the currents are too high. The Compass Bs also offers an optional diagnostic feature that monitors the state of the switch field and from which the master display can be queried. The integration of the remote control unit in the Compass Bs minimises the remote control device’s features and saves additional costs. The Compass Bs can be integrated into switchgears of any manufacturer.


Functional enhancements in devices such as the SIGMA F+E 3i, Sigma D/D+ and Compass Bs enable these devices to offer additional intelligent features to automate the medium voltage distribution network. A medium voltage switchgear used with the new current sensors and the voltage detecting system Wega 1.2 C/2.2 C/1.2 C vario are also ‘ready for retrofit’ for future enhancements. Functional enhancements can be performed later by replacing the devices, such as the Sigma F+E 3 with the Sigma D/D+ or the Compass B with the
Compass Bs, without adjusting the current and voltage sensors.


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