NT & NQ CLASS II TRANSFORMERS FOR SIGNALLING SYSTEMS A Balfour Beatty and Alstom Company
NT Transformers CLASS II DOUBLE INSULATED HYBRID TRANSFORMERS / LOW POWER-T/J COMBINED UNITS FOR RELAY AND SSI SIGNALLING SYSTEMS 650V /230V /11 OV /.. The signalling transformers provide the interface between Class II (Double Insulated) 650/440/400V power system and 1V signalling systems. The outputs include multiple 1V/1211135V a.c. and for signalling, or 230V for telecoms and Hot Axle Box detectors, all depending on part number chosen. The transformers comply with NR/L2/ SIG/3007 Issue 2 and allow system compliance with Electricity at Works Regulations and NR/SP/ElP/27243. Each transformer provides an 8kV minimum impulse withstand voltage in compliance with BS7671 to provide additional protection against ground potential rise, particularly in areas with d.c. or a.c. traction systems. The application of the transformer range must take account of the Network Rail circuit recommendations, testing recommendations, the conditions of use/approval of any equipment powering and being powered by the transformer and associated rectifiers, and the specific approval of each of the transformers in the range. Refer to the table for the approval reference number (PADS number). The transformers generally operate from a 650V single-phase signalling distribution system or two wires of a 650V three-phase signalling distribution system. The Double Insulated (Class II) range allows considerable economies in the 650V distribution system powering the location cases by removing the need for an earth conductor. In order to reduce lifetime operating costs, the transformers are designed to minimise standing losses. The transformer secondary a.c. outputs are generally single-phase isolated windings designed to power Relay and SSI signalling equipment. Many transformers are provided with up to four isolated 1V/135V outputs to allow Points TFMs to be provided with control power without a separate 135V transformer. The 135V tap is suitable for use on a Points TFM 135/140V input when configured for indirect points drive power from a suitable NO series rectifier. Low power. unsmoothed unregulated outputs are included on many models. This. output can be used for driving relays etc associated with Relay or SSI signalling schemes. Transformers NT67, NT6720, NT6722, and NT6731 include this feature and are known as Low Power T J Combined Units. The. feature generally removes the need for external 1V/50V rectifiers with a consequent reduction in space and interconnection wiring in the location case containing the transformers and signalling equipment. 2
NT Transformers Part Number Weight kg Voltage (Single phase unless shown) Input Fuse A Note 3 Isolated Windings a.c. & d.c Voltage (Note 5 for d.c. outputs) Main Taps (Note 1) Output Output Power VA (per output) 135V Tap. (unless shown) Note 5 Total VA Note 7 Max Fuse (Short CCT) A Note 2 PADS Catalogue Number NT6703 11.75 650 2 1 1 250 250 15 86/045920 NT67 11.75 650 2 2 400/350 50 200 500 86/045921 NT6712 11.75 650 2 1 1 500 500 15 86/045928 NT6720 22.5 650 4 3 1,135 425/375 50 1,135 150 00 425/375 50 86/212524 NT6722 23 650 4 2 230 15 850 150 00 86/045929 NT6723 22.5 650 4 1 1 00 00 15 86/045923 NT6731 29.75 650 6 6 NT6750 20 650 6 2 1 1, 140 300/250 300/250 300/250 500/450 130 1500/20 50 50 50 50 750 (1400 Intermittent) 0 0 1600 1650 5 15 86/212525 86/045930 NT6760 47 650 6 1 230 3000 3000 16 86/045931 NT6761 47 650 6 1 1 3000 3000 32 86/045926 NT6763 47 400/440 1 230 3000 3000 16 86/045932 Note 1 Rating of main and subsidiary taps Where the rating of main a.c. tap is shown as xxx/ yyy The lower rating (yyy) of the main secondary tap is used if the 135/140V tap is loaded with its rated load. The higher rating (xxx) may be used on the main tap if the 135/140V tap is not used The available rating on the main tap is xxx-yyy if part load is used on the 135/140V tap Intermittent rating refer to 3.1 Outline of Transformer range. The total continuous power drawn from each winding must not exceed the rated power capability of the winding except for the NT6722 230V winding. (Ref Note 7) Note 2 Max fuse rating on secondary The Output fuse rating in 4.1.1 is for close short circuit protection only Smaller fuses on individual loads must be fitted to provide overload protection Secondary fuses must clear the short circuit within the time specified in Max Duration of Prospective fault current (Table 4.1.1 above) The loop impedance of the secondary circuit must be low enough to clear the secondary fuse before the transformer is damaged The two fuse values in one row are the respective values for a winding providing 1V and 135V. e.g. for NT67 the 1V fuse is 5A and the 135V tap fuse size is 2A NT6760 and NT6761 will start and run on a 4A fuse with reduced load if utilised on a weak 650V supply NT6763 will start and run on a 6A fuse with reduced load if utilised on a weak 400V supply Under these conditions the maximum load of NT6760, NT6761 and NT6763 must be limited to 1500VA Note 3 Fuse type Primary fuses BS88 fuses or IEC 60269-1 & -2. for 650V BS1362 primary fuses may be used for 230V TN supplied primaries Secondary fuses BS88 or IEC 60269-1 & -2 fuses are used above 15A rating or above 175V 1V fuse range is Littlefuse 326.XXX range up to 15A Note 5 Inrush specified as Inrush/Rated current (Rated current = Amps RMS, Inrush = Amps Peak) Note 6 The outputs of multiple windings must not be connected in parallel as this will cause circulating currents which will change the thermal performance of the transformer and potentially affect reliability Note 4 NT6722 achieves a nominal 230V (TN) by utilising two nominal 115V windings in series Terminal 0 is normally internally connected to earth (TN) The two windings are internally interconnected by Link A or Link B to provide a single 230V winding Link 115(A) to L to provide 220, 225 or 230V taps Note 7 The total power drawn from all windings simultaneously must not exceed the total power capability of the transformer (Total VA) e.g. NT67 can supply up to 400VA on the 1V a.c. output and up to 200VA on the. output However Total load on NT67 must not exceed 500VA Thus NT67 capacity - a) 300VA at 1V can be supplied at the same time as 200VA at 50V OR b) 400VA at 1V can be supplied at the same time as 0VA at 50V Link 135(B) to L to provide 240, 245 or 250V taps Link B and 240V is factory setting Maximum output power at 230V is 850VA if the 50V d.c. output is used If any power is drawn from a 5/1/115V tap then maximum winding current measured on 0V (a.c.) connection must not exceed 3.7A NT6722 can supply up to 800VA on the 230V a.c. output and up to 150VA on the. output However total load on NT6722 must not exceed 00VA Thus NT6722 capacity - a) 850VA at 230V can be supplied at the same time as 150VA at 50V OR b) 00VA at 230V can be supplied if no load is applied to the 50V winding Note: b) applies to NT6722 only, the maximum winding rating must be observed on all other transformers 3
NQ Transformers CLASS II DOUBLE INSULATED HYBRID TRANSFORMER/RECTIFIER FOR RELAY AND SSI SIGNALLING SYSTEMS 650V to 120V The signalling transformer/rectifiers provide the interface between Class II (Double Insulated) 650V power systems and 120V d.c. points machines, in a signalling system. The construction of the transformer in the transformer/rectifier allows system compliance with Electricity at Works Regulations and NR/SP/ELP/27243. The internal transformer complies with NR/L2/SIG/30007, Issue 2. The internal transformers provide 8kV minimum impulse withstand voltage for supplies greater than 170V in compliance with BS7671 to provide additional protection against ground potential rise in areas with d.c. or a.c. traction systems. The application of the transformer/ rectifier range must take account of the Network Rail circuit recommendations, testing recommendations the conditions of use/approval of any equipment powering and being powered by the transformer and associated rectifiers and the specific approval of each of the transformers in the range. Refer to the table for the approval reference number (PADS number). The transformer/rectifiers generally operate from a 650V single-phase or three-phase supplies (connected via two or three wires of the power system). The Double Insulated (Class II) range allows considerable economies in the 650V distribution system powering the location cases. The Double Insulated range is described in data sheets designated NT67xx (Transformers) and NQ67xx (Rectifiers). In order to reduce lifetime operating costs, the transformers in the rectifiers are designed to minimise standing losses. Transformer/rectifiers are available for driving one, two or four points machines from the Clamp Lock, HW, HPSS or Hi-Drive range. The number of points machines that may be driven from a particular rectifier must be selected by the user to be compatible with the output capacity, current/ time profile and repetition rate of the chosen points machines. The rectifier outputs are intended to be controlled by Relay or SSI TFM points modules (PM) that indirectly drive electric points machines e.g. via contactors (Ref: NQ67XX data sheet). Points machines (e.g.clamplock) that are directly driven from the Points modules should use transformer NT6750 (for 650V systems) which has a separate 140V winding for this use. 4
NQ Transformers Part Number Weight kg Voltage (1 phase unless shown) Input BS88 Fuse Note 2 Qty of Points machines Note 4 HW Hi Drive HPSS NQ6720 23 650 6 2 1 2 Output Voltage and Available Taps (a.c. to rectifier) Voltages below are a.c. unless shown Note 3 135/6.5V. FOR 120/94.5V d.c. NQ6730 650 4 2 1 2 120 d.c. smooth NQ6740 32 650 4 3 2 135/6.5V FOR 120/94.5V d.c. NQ6750 650 6 4 3 4 120 d.c. smooth Max Fuse Note 1,2 PADS Catalogue Number 54/212526 54/212527 Note 1 Max fuse rating on secondary Note 2 Fuse type - Input The fuse rating specified is for short circuit protection only Short circuit protection must be provided by output fuses on individual points loads when more than one point machine is driven by any rectifier and always for NQ 6730, NQ6740 and NQ6650 Short circuit protection may be provided by primary fuses on NQ6720 if only one points machine is driven. In this case 120V secondary fuse need not be fitted The loop impedance of the transformer/rectifier system, including the cables to the points machines shall be designed to allow more than 0A to flow in the event of a short circuit at the most remote points machine BS88 fuses are used for ratings above 15A or above 250V. BS1361 or BS88 fuses are used on 230V Fuse type output Fuses to meet note 2 requirements shall be provided If individual points are fused in the same enclosure as the Transformer/rectifier using Littlefuse 326. XXX range up to 15A The primary fuse can protect a single cable that takes 120V d.c. outside the enclosure housing the transformer/rectifier for remote distribution using Littlefuse 326. XXX range up to 15A. The loop impedance of the 120V circuit must ensure that 0A can flow from the rectifier under fault conditions Note 3 Single-phase output voltage depends on output tap selection (135V or 6.5V) 120V d.c. output with 135V tap selected from full wave rectifier unsmoothed, expressed as mean d.c. 94.5V d.c. output with 6.5V tap selected from full wave rectifier unsmoothed, expressed as mean d.c. 1. smooth output with 6.5V tap selected from full wave rectifier with external smoothing expressed as d.c. The measured d.c depends on the size of the smoothing capacitor and will be lower with a small smoothing capacitor Three-phase output voltage 120V d.c. output from three phase units is 6 pulse rectified d.c. which provides a substantially smooth d.c. Note 4 Ref 4.1.1 Designer data for maximum number of points machines that may be driven by each of the rectifiers 5
Transformer Dimensions TRANSFORMER DIMENSIONS Transformers and Transformer Rectifiers are of robust construction and are suitable for housing in Standard Pattern location cases fitted with suitable supporting rails. They include a fully insulated concentric copper earth screen fitted between primary and secondary windings. They are housed in unventilated vermin proof cases completely protecting the terminals and windings. All connections are made to terminal blocks inside the Transformer and Transformer Rectifier case. NT6703 200 2 OFF 25 CABLE ENTRY NT6722 270 5 OFF 25 CABLE ENTRY 2 OFF ON LEFT 3 OF ON RIGHT NT67 NT6712 275 MAX NT6720 NT6723 275 NT6731 330 200 260 200 NT6750 NQ6720 115 115 300 230 NT6760 370 MAX 2 OFF 25 CABLE ENTRY 270 MAX NQ6730 350 5 OFF 25 CABLE ENTRY 2 OFF ON LEFT 3 OF ON RIGHT NT6761 NT6763 325 MAX NQ6740 NQ6750 270 420 4 200 115 150 380 390 6
Transformers Operating Environment OPERATING ENVIRONMENT Transformers are designed to meet the following conditions. EN 50124-1:2001 Railway applications. Insulation coordination Part 1 Basic requirements Clearances and creepage distances for all electrical and electronic equipment. Note EN 50124-1 is derived from BS EN 60664-1 Transformers with a 650/440/400V primary will withstand an 8kV test voltage specified in the 400V/690V row of BS7671:2001 Table 44A or BS7671:2008 table 44.3 (EN50124-1:2001 Clause B2.1) The transformer is suitable for continuous operation full load operation at ambient temperatures between 25 C to +70 C. (BS EN 50125-3:2003 Railway Applications Environmental Conditions for Equipment - part 3: Equipment for Signalling and Telecommunications) BS EN 50121-4 Railway applications. Electromagnetic compatibility. Emission and immunity of fixed power supply installations and apparatus restricted to BS EN 600-4-4 (transients) and BS EN 600-4-5 (surges) in relation to d.c. outputs of the transformer range The transformer/rectifiers shall be suitable for operation at ambient temperatures between -25 C to +70 C with the defined current demand and duration of the specified points machine/level crossing type with a maximum repetition rate of 120 seconds or more. Ref 3.4.7 below. (BS EN 50125-3:2003 Railway Applications - Environmental Conditions for Equipment - part 3: Equipment for Signalling and Telecommunications) HANDLING Lifting facilities to aid manual handling are provided as applicable. A lifting frame 086/045843 (NQ6690) is available to allow movement of a heavier Transformer and Transformer Rectifier in accordance with the users appropriate risk assessments as described under the Manual Handling Operations Regulations 1992 7
excellence in train control Signalling Solutions Limited Bridgefoot House Watling Street Radlett Hertfordshire WD7 7HT Telephone: +44 (0) 1923 635000 Facsimile: +44 (0) 1923 635086 Email: info@signallingsolutions.com www.signallingsolutions.com URBALIS, ATLAS, SMARTLOCK and ICONIS and any alternative version thereof are trademarks and service marks of ALSTOM. The other names mentioned, registered or not, are the property of their respective companies. The technical and other data contained in this document is provided for information only. ALSTOM reserves the right to change this data at any time without further notice. Photo credits: ALSTOM, ALSTOM Transport / P. Guignard / P. de Salabert / TOMA- C. Sasso, GettyImages / Michael Wheatley info@signallingsolutions.com