BS/EN 50152-3-1-2017 pdf download.Railway applications Fixed installations Particular requirements for a.c. switchgear Part 3-1: Measurement, control and protection devices for specific use in a.c. traction systems — Devices.
3.1
under-voltage
voltage the value of which is lower than a specified limiting value
[SOURCE: IEC 60050-151:2001, 151-15-29J
3.2
under-voltage off
control function which permits a mechanical switching device to open, with or without time-delay, when the voltage of the circuit the mechanical switching device is connected to falls below a predetermined value
Note 1 to entry This term is used when a lass of primary voltage is considered.
Note 2 to entry This function will en most cases require any kind of shunt release.
3.3
under-voltage release
shunt release which permits a mechanical switching device to open or close, with or without time-delay, when the voltage across the terminals of the release falls below a predetermined value
[SOURCE: IEC 60050-441:2000, 441-16-42]
Note 1 to entry This term is used when a loss of an auxiliary voltage is considered
3.4
under-voltage trip
protection function which permits a mechanical switching device to open, with or without time-delay, when the voltage of the circuit the mechanical switching device falls below a predetermined value
Note 1 to entry This term is used when a lass of primary voltage is considered.
Note 2 to entry This function will in most cases require any kmd of siiunt release.
4 Specific requirements from the traction system
Traction systems due to e.g. their load, voltage and earthing conditions require thorough analysis when defining operational principles and requirements for equipment.
The design of measurement, control and protection circuits, their devices and algorithms shall consider any effect arising from:
— fast fluctuation of traction power demand;
— moving tractions units, providing scenarios with traction currents higher than failure currents;
— the return current system. especially the track, effectively connected to earth:
— fast fluctuation of operating voltages between Urn and Limax2, with Urm, and U, as specified in
EN 50163:
— high number of switching operations eg. caused by a high number of short circuits in the contact line systems:
— in 16,7 Hz traction systems the duration of a period of 60 ms in respect to magnetisation. saturation and switching times;
— in auto-transformer systems, a phase shift of 180’ resulting in an maximum operating voltage of 2 Umaz but only between phases.
NOTE 1 The return circuit In a.c. traction systems Is effectively earthed, Unlike utility networks a displacement of the star point during earth faults resulting in an increase of phase voltages by factor 3 cannot happen.
NOTE 2 Equipment in a 25 kV traction system is subject to a maximum permanent operating voltage phase to earth of 27,5 kV = U,,i. Equipment in a 3 phase utility network with a highest system voltage Urn = 36 kV has an average continuous voltage phase to earth during 99% of its life of 33h’3 kV = 19.1 kV.
If the above values are compared, it becomes clear that the dielectric stress of equipment in traction power supply is significantly higher and therefore the test voltages e.g. during partial discharge testing have assigned higher values In this European Standard.
5 Requirements on measurement, control and protection devices
5.1 General
Measurement, control and protection devices shall be designed, manufactured and tested to their specific product standards, Requirements of railway standards prevail and shall be applied as far as reasonably possible. This especially concerns EN 50124-1 for insulation coordination and EN 50121-5 for electromagnetic compatibility.
5.2 Voltage detection systems
Capacitive voltage detection systems shall comply with EN 61243-5 except for the following requirements:
— voltage absence indication shall be below 50 % of Umin2,
— voltage presence indication shall be above 90 % of Umr2 and
— the capacitive voltage detection system shall property work also up to U.2.
NOTE I The thresholds for voltage absence and presence indication are adapted considering the fact that voltages are between contact line and running rail on ground potential and also the tolerances of supply voltages of traction systems.
When selecting voltage detectors manufactured according to EN 61243-1 it may be preferential to use thresholds for voltage absence and presence indication as specified before.
NOTE 2 This portable equipment Is only temporarily connected to a supply voltage of the traction system.
NOTE 3 There are national standards available in some countries specifying thresholds for voltage absence and presence Indication.
5.3 Devices at supply voltage of a traction system
Devices not covered by a railway specific product standard and being connected to a circuit at supply voltage of a traction system shall comply with the test voltages including partial discharge level as specified in EN 50152-3-3 for this supply voltage. If these devices are connected to provide isolation of feeding systems the test voltages shall be taken for across the isolating distance from EN 50152-2:2012, Table 1 e.g. when connected parallel to a disconnector.
Other requirements of EN 50152-3-2 or EN 50152-3-3 or for sensors as given in the EN 61869 series shall apply as far as reasonably possible and shall be agreed upon between supplier and infrastructure manager.
Devices containing electronic parts shall be subject to a function test in the intended operational Circuit and under worst case conditions e.g. in its installation position next to a circuit breaker during a short Circuit breaking test.
Dielectric type tests shall be applied as specified in EN 61869-1:2009, 7.2.3 with test values as specified in EN 50152-3-3:2016, 7.1. BS/EN 50152-3-1-2017 pdf download.

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