In the Netherlands, two different traction energy supply systems are in use on mainline railways. The standard supply voltage for railway lines is 1500 Vdc. The newly built Betuweroute freight line and the high-speed line Amsterdam-Rotterdam-Antwerp however have been electrified with 25 kV, 50 Hz. It was anticipated that under specific fault conditions, stray currents from a DC line could flow in the return circuit of a nearby AC line, exposing for example transformers to DC effects. Prolonged exposure to DC effects may damage the main transformer on board of a train. In order to assess the risk, on-board measurements may be required.
In order perform such measurements relatively easily, EMPEQ has developed a portable data logger which can be placed on board of any train permitted to run on a 25 kV electrified line in the Netherlands.
The instrument is equipped with a number of high-precision Direct Current Transformers (DCCTs). One DCCT is mounted on each of the cables connecting the main transformer’s return connection to the return current brushes of the train or locomotive.
The instrument logs the DC component in 10-second intervals. It is equipped with a GSM modem to transmit measured data to a remote server and to send an alarm SMS if a pre-set level of DC is exceeded.
Technical specifications:
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Supply voltage
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110 Vdc
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Type of DCCT
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LEM IT400-s
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Number of DCCTs
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8
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Max. current per DCCT
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400 Arms
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DC accuracy
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± 50 mA
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Logging interval
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10 seconds
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The instrument has been successfully tested against the following EMC standards:
EN61000-6-4:2007 Generic emission standard for industrial environments
EN61000-4-2:1995 Electrostatic discharge immunity
EN61000-4-3:2006 Radiated electromagnetic field immunity
EN61000-4-4:2004 Electrical Fast Transient (EFT) immunity
EN61000-4-5:2006 Surge Transient immunity
EN61000-4-6:1996 Conducted Radio-frequency disturbances immunity
EN61000-4-8:1993 Power frequency magnetic field immuity
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