POWER
New medical power supplies balance high reliability and low cost
Emerson Network Power has added two new models to its popular LCM series of AC-DC power supplies, which is known for providing high reliability with medical and industrial safety approvals - at a very competitive cost.
With the addition of the LCM300 and LCM1500, rated for 310 W and 1,500 W loads, alongside the existing 600 W LCM600 unit, Emerson’s LCM series can now provide for a very wide range of AC-DC embedded power requirement.
The LCM series medical safety approvals are compliant with the third edition of the ANSI/AAMI ES60601-1:2005 / IEC 60601-1 medical safety standard. Their medical safety compliance extends to providing MOPP (means of patient protection) and the complete risk management files required by the 3rd edition. Emerson’s quality management system is geared towards removing the burden and expense typically placed on the end-product designer in achieving product compliance. Variable-speed ‘Smart Speed’ fans draw on software controls
developed by Emerson Network Power to match fan speed to the unit’s cooling requirement and load current. Slowing the fan not only saves power but also reduces wear, thus extending its life. The LCM series maintains Emerson’s high standards of quality and reliability,
Emerson Network Power LCM series
demonstrated by a MTBF of greater than 500,000 hours under normal operating conditions, and the units carry a manufacturer’s warranty of three years. For more information visit
avnet-abacus.eu/emerson
New Vishay resistor serves alternative energy applications
m. dressler and b. sChott
Power resistors are being used in a steadily growing range of applications driven by the increasing demand for renewable energy and energy recovery. Basic applications like brake, chopper, and crowbar resistors aren’t new, but their use in hybrid or electric vehicles, as well as wind and water power turbines, poses a challenge in terms of size and reliability. Vishay’s new ULDCR series of ultra-compact power resistors addresses these issues. Featuring an innovative, self-supporting design of thick, laser-cut meander plates, ULDCR devices are guaranteed to provide extreme robustness against magnetic forces.
The typical characteristics and advantages of this design can be seen by looking at a typical model: the ULDCR25. The ULDCR25’s nominal resistance is 0.8 Ω, and it can pick up pulse energies of 2 MJ. This is why it weighs a respectable 24 kg, but occupies only a volume of about 13 liters at a footprint of about 60 cm x 20 cm. Only some fraction of the device volume is occupied by the active part of the resistor, leaving voids for air circulation and limiting the cool-down time between two consecutive pulses to only about one hour in case of unforced cooling (i.e. by natural convection). Higher pulse repetition rates can be achieved by increasing the void space, but this would increase the total size. The volume can be sized down still further by using less void space, but this increases the cool-down time. The size of the bare resistor (IP00) also depends on the permissible surface temperature. 300 °
C is a typical excess temperature. Vishay “ULDCR25” crowbar resistor.
A smaller size would lead to a higher temperature. But even temperatures of about 900 °
plates and mica are used for its construction.
Laser cutting of the steel plates allows for virtually unlimited design flexibility. Steel plates can easily be as thick as 10 mm allowing pulse currents of 10 kA. A special self supporting construction enables the resistor to cope with the high magnetic forces generated by the high current. For more information visit
avnet-abacus.eu/vishay
11 focus magazine - issue 14
C do not damage or degrade the resistor, because only steel
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16