TECHNOLOgy REvIEW


leads rather than terminal connections. Its input range is 90-264VAC (at 47-63Hz) with a fully isolated output delivering 250W total power (either 12V @ 20.8A or 24V @ 10.4A). However its ingress rating is only IP64 compared to the Delta unit, with full dust sealing but only water splash protection.


pcb-mountAble power supplies This final category embraces DC-DC converter modules that are suitably rugged to meet the requirements of transport applications but are provided with pinned connections and intended for mounting on printed circuit boards.


Power-One (Melcher) offers the IMX series of PCB-mountable DC-DC converters, which are designed to meet industry requirements for railway and transportation applications and include models rated at 15W, 35W and 70W. The


Figure 5. Power-One’s IMX35 PCB mount DC-DC converter


IMX35 series, shown in figure 5, offers versions handling input voltages up to 150V with each module providing 4 outputs supplying up to 60V. These units feature careful thermal design, without using potting materials, allowing full load up to an ambient temperature of 71oC in free air or 105oC with airflow. To contend with extreme high vibration environments the case


has holes for screw mounting avoiding any reliability issues through depending on just the solder connection pins. Last but by no means least is the RUW15


series of 15W single-output converters from Murata-PS. These units are very compact, measuring 50.8 x 50.8 x 20mm and featuring mounting lugs to fix to the circuit board. A very wide input range of 16-160VDC allows for the many input voltages encountered in railway applications and largely eliminates requirements for surge protection. The four models cover two output voltages, either 12V @ 1.25A or 24V @ 0.625A, each with the option of a Power Fail / DC OK signal. All outputs are protected from overvoltage and short circuit and operation is specified for ambient temperature of -40oC to +85oC but allowing for a case temperature rise of 40oC with thermal protection.


Ultra wide 8:1 input range DC-DC converter designed for railway applications


Murata has recently launched the UCR100 series of DC-DC converters designed specifically for railway power conversion and battery applications. Accommodating an ultra wide 8:1 input range, from 16.8 to 137.5 vDC, the UCR100 series comprises 3 single output models providing 5, 12, or 24 vDC outputs. Additional model- specific options include current share, holdup and an adjustable undervoltage lockout feature. Packaged in a Euro Cassette format measuring 3U x 4TE x 165 mm, the UCR100 series is footprint and pin compatible with competitive product offerings. The UCR units offer customers ease of installation and better energy efficiency ratings than comparable models. Typically a single UCR module can take the place of up to 5 alternative modules currently used in customers’existing applications. The series also can improve overall system reliability through use of the input hold up option that requires just a single capacitor to provide up to 10 ms holdup. These highly efficient units, typically up to 90%, create less heat than other power supplies and ensuring no extra forced air cooling is required. They are packaged in a ruggedized enclosure and conformally coated in order to achieve high standards of reliability and resistance to the effects of moisture. Mounting methods can be in a 19” rack or bolted to a bulkhead. The UCR100 series provides tight line and load regulation together with control features such as remote On/Off, a +/- 10% output trim and a remote sense of +/- 10%.


The active current share option allows multiple UCR converters to connect in parallel to support higher output currents or to achieve higher


9 focus magazine - issue 15


system reliability through redundancy.


The UCR100 series conforms to all relevant transportation industry safety standards including EN50155, EN50116, IEC60571, RIA12 and IEC/ EN/UL60950-1. For more information contact avnet-abacus.eu/murata


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