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Thermal Management For Power Supplies

To make sure your power supply runs efficiently for the long run, you need to remove heat from the device. Here are some ways that Polytron uses appropriate thermal management strategies to increase the mean time before failure (MTBF) and keep temperatures down in all our power supplies.

HWB100Potting Material. Using a thermally-conductive potting material helps dissipate heat while helping with shock and vibration. These potting materials feature a low thermal resistance and help carry heat away from the power supply electronics, improving cooling efficiency.

Forced Air Cooling. Forced air cooling speeds up heat dissipation to extend the life of our power supplies. In this method, a fan blows outside cool air across the top of the power supply. One of the biggest advantages of forced air cooling is that it requires little maintenance.

Heat Sinking. Internal heat sinking eliminates heat from inside power supplies by dispersing heat for improved efficient energy use. Bringing the heat sink to its outside surface allows for a more direct airflow to reach the direct source of heat. This method radiates heat so it doesn’t get trapped inside and over heat the power supply.

Conduction Cooling. Conduction cooling is sometimes used in our high wattage power supplies. This method mounts all internal heat sources to an isolated metal baseplate, which is then mounted to a heat sinking frame or housing.


How to diagnose power supply problems


Before leaving the plant, power supplies are always subject to performance testing. These tests include line regulation at full load and operating temperature.

The problem with these ideal testing conditions is that there's no guarantee that the operating conditions of a power supply will be consistent with the test conditions. One reason for this is that electrical components have performance tolerances – the most common being 5, 10 and 20 percent of the nominal value. This component tolerance effect is additive, which can keep the power supply from working properly.

Once you've ruled out tolerance issues, here is how you can diagnose a power supply problem.

No Load. Start by testing the power supply on a bench with no load. If it doesn't work, you'll know right away to contact the manufacturer for another unit. If the power supply works, you should test it with a resistive load to see if that's the problem.

Resistive Load. Failure with a resistive load can mean that your tolerances have caused a process or component failure. Other possible reasons for failure with a resistive load are if the component is out of specification or has a cold soldered joint. If the power supply still works with a resistive load, you'll want to test it with an active load.

Active Load. If the problem comes from the active load, it could be due to an unfamiliar signal caused by high capacitance. A large capacitor on initial power-up can act as a short circuit, forcing the unit into short circuit protection. At this point, you should check the manufacturer's specification to see if your unit has exceeded the maximum capacitive load.

If your power supply still doesn't work, you have two other options: either lower the capacitive load, or get a different unit with circuitry that can handle higher currents.

Robust DC/DC converters meet railway requirements

Railway electrical systems can be tough on DC/DC converters. That’s because the converters have to contend with a multitude of background signals that can cause interference.

Air-conditioning, lighting, broadcasting and fire systems can prevent DC/DC converters from working the right way.

Railroad-Ready DC/DC Converters. Our quarter and half brick DC/DC converters for railway applications are designed for efficiency in these conditions. Also offered with a 24 pin DIP package of 1.25” x 0.80” x 0.40” or an industry standard package of 1.0” x 2.0” x 0.40,” these DC/DC converters come in a variety of wattages and meet all EN50155 requirements including input, electromagnetic compatibility, mechanical, thermal and isolation. They also feature adjustable output voltage and no minimum load requirement.

DC/DC converters that meet EN50155 standards specify a nominal input variation of ±30%, including ripple. Most trains achieve weight and space savings by using battery voltages up to 110 Vdc. However, most system equipment requires input power between 12 and 24 Vdc. DC/DC converters that meet these standards transform the basic 110 Vdc to 12 and 24 Vdc.

Technical Features. Our DC/DC converters protect electronic railway equipment against dielectric strength through different isolation barriers. For 24 and 48 Vdc nominal input, EN50155 requirements for rolling stock are 500Veff/50Hz/1min. For 72 to 315 Vdc, the requirements are 1.500Veff/50Hz/1min.

Our internal noise solutions make for very clean signals both to and from the DC/DC converters to optimize overall operation. The DC/DC output is maintained for 10 milliseconds during power outages.

These converters also pass shock and vibration testing for harsh environments. Shock load tests have accelerations as high as 5g for 50 ms, while vibration tests require accelerations up to 5g frequencies up to 150 Hz.

Other features include under voltage, output current, short circuit, over voltage and over temperature protection. Their ability to survive harsh environments with high shock and vibration loads helps reduce premature system failures in railway applications. 

Extend the life of your power supplies

When choosing a power supply for your electronics application, pay close attention to its input voltage range. Sounds obvious, but engineers often forget to consider the possible range of input voltages their product will see in the real world. The result can be a reduction in the lifecycle of the power supply.

Our linear power supplies are known for their reliability, with a very conservative mean time between failure (MTBF) specification of at least 710,000 hours when run within an input voltage range that spans ±10 volts from nominal. But these supplies can last far longer than that if they run at the lower end of this input voltage range.

For example, a power supply designed to work at 220 Vac will operate within a range between 210 and 230 Vac. Consistently operating at the lower end of that range will keep your power supplies cooler and increase their lifespan substantially.

It’s not uncommon to see at least a 25 percent improvement in power supply lifecycle by operating at the low end of the acceptable input voltage range.

At the same time, consistently running the power supply at the high end of its input voltage range will keep it from reaching its maximum lifecycle potential, even though it will still meet the published MTBF spec.

Bottom line is that cooler power supplies will run longer than hotter ones. And one way to turn down the heat is to pick supplies so that operate at the lowest possible point on their input voltage range.

Reliable Power Supplies For Medical Applications

Looking for a safe, reliable way to power medical equipment in hospitals, doctor’s offices or in home health care settings? Our DC-DC converters and AC-DC converters meet a precise set of safety specs and requirements, making them ideal for applications involving patient contact.

Safety first. Our DC-DC converters and AC-DC converters can safely be used for a variety of medical machines including:

  • Diagnostic and therapy equipment.
  • Nebulizers and blood pressure monitors.
  • X-Ray machines.
  • Surgical tools.
  • Defibrillators.
  • Portable ventilators.

All our medical power supplies feature a low leakage current to prevent electrical shock from direct contact with equipment.

Packaging styles for AC-DC converters. Our AC-DC converters typically come with an open frame packaging style. To better meet your power supply needs, we also offer three other options:

  • Chassis mount.
  • Enclosed type.
  • DIN rail mount.