China Safety Standard- Higher Clearance for Power Supplies

We used to think that if our power supply design meets IEC or corresponding UL requirements for a given application, we would automatically meet most national standards of other countries. Now, the main ITE Standard in China GB 4943.1-2011 appears to set more stringent requirements to ITE equipment. Although in general, GB 4943.1-2011 is based on IEC 60950-1 2nd addition, it includes certain deviations. Particularly, par.1.1.2 states that unless specified by manufacturer, the equipment is to be used up to 5000m altitude above sea level. Therefore, in the absence of the marking of par.1.7.2.1 specifying the altitude below 2,000 m, the equipment shall comply with the requirements for 5000m altitude. For such equipment, the minimum electrical clearance has to be multiplied by the factor of 1.48.
In many offline SMPS the minimum UL required creepage between primary and secondary circuits is 6.4mm. If both primary and secondary circuits are located on the same side of PCB, this number also determines the spacing (clearance) between the circuits. With the new China standard that goes into effect December 1, 2012, this spacing will now have to be greater than 9 mm. Note that GB 4943.1-2011 will apply to not only the devices for use in the China, but to all those produced there too. So, if you manufacture power supplies in China, in my understanding, you either need to redesign the PCB and replace certain surface mount optocouplers (if any), or add a warning label showing that your PSU is not for use above 2000m.

Connecting An Emergency Generator

There are two basic methods of connecting your devices to an emergency power generators:

• Via a pre-wired transfer switch;
• Via extension cords.

The transfer switch method can be used for both stationary and portable generators. Portable generators are connected via a manual transfer switch. The stationary standby home systems usually use an automatic transfer switch. It automatically isolates your home from the grid and starts up the generator when it detects a power outage.
A transfer switch installation and wiring requires a licensed electrician and obviously takes time. If you are caught off-guard by a blackout, you’ve got to use a portable genset with extension cords. This is the case today, when more than 3 million people in mid-Atlatic are still without power after a sudden storm. Unlike hurricanes that give you about a week of warning, this storm gave all the impact of a hurricane without any warning. Unfortunately, the extension cords can be used only for cord-and-plug appliances. Connecting lights and hard-wired appliances to a portable generator will not be simple. There are some emergency methods of connecting hard-wired devices, but they may require a professional help. In any case, here are the main two things you need to remember:

• Whenever you run a generator, it must be isolated from the utility lines;
• A generator can be run only outdoors with exhaust pipe located away from house.

New Proposed Efficiency Standards for Battery Chargers and External Power Supplies

U.S. Department of Energy recently issued Battery Chargers and External Power Supply (BCEPS) Notice of Proposed Rule. DOE proposes amended efficiency standards for Class A external power supplies (EPSs) and new standards for non-Class A EPSs and battery chargers. The proposed standards set the minimum average efficiency in active mode and the maximum power consumption in no-load mode as a function of the nameplate output power. The greatest challenge for SMPS power supply designers in my view will be the proposed limit of maximum power in no-load mode. For EPS below 50 watt it will be <0.1 watt. Since a power supply has to be able to “wake up” when connected to a load, it needs to keep active certain control circuit. Keeping a consumption of an off-line bias supply below 0.1 W will be a real challenge.

The U.S. Department of Energy (DOE) will hold a public meeting on May 2, 2012 to discuss the analyses presented and issues identified in the Notice of Proposed Rulemaking and Technical Support Document. These proposed standards, if adopted, would apply to all applicable external power supplies manufactured in, or imported into, the United States on or after July 1, 2013.

At abote the same time, U.S. Customs and Border Protection (CBP) issued a notice of proposed rulemaking about Consumer Products and Industrial Equipment Non compliant with applicable Energy Conservation or Labeling Standards. CBP will refuse admission into the customs territory of the United States to consumer products and industrial equipment deemed non compliant with the Energy Policy and Conservation Act of 1975 (EPCA).

I feel our government is just one step short of stopping anyone at the border for carrying a cell phone with non-efficiency-compliant charger.