Wednesday, October 31, 2007

2.2kV Transistor with Innovative Package

We often hear about applications where a high voltage transistor would be useful. STMicroelectronics has recently introduced a 2.2kV transistor. It's a hybrid emitter switched bipolar transistor. There are several parts in this family including the 2.2kV, 3A

As if the voltage rating wasn't enough, what makes it especially interesting is a notch between the collector pin and the other pins in the TO-247 type package. The notch serves to increase the creepage voltage (see glossary at to permit the part to operate at higher voltage than a typical TO-247 device.

For more information, see the spec sheet at

Monday, October 29, 2007

New Transient Suppressor Manufacturer

A new family of ultra-low capacitance Transient Voltage Suppressor (TVS) products was released earlier this year from Alpha and Omega Semiconductor, Inc.

They have products that meet IEC61000-4-2 Level 4 specification for electrostatic discharge (ESD) protection (8kV for contact and 15kV for air discharge).

They also have products that provide protection to 15kV for contact and 18kV for air discharge, which far exceeds the IEC61000-4-2 Level 4 specification.

Capacitance is as low as 0/9pF. I'd agree that this is ultra-low for TVS devices.

These products are worth looking at when protecting parts of HV systems from such transients as arcs, lightning, and pulses. See

Friday, October 26, 2007

High Voltge Capacitor overview

What makes a capacitor identifies as "high voltage" is a rating above 2kV. That's because there are many manufacturers that build capacitors rated up to 1600V or 2000V. (This is in accordance with my definition of high voltage, "High voltage starts at the point where designers have to consider additional technical issues, and where there are significantly fewer component suppliers to choose from. " Typical dielectrics used for high voltage capacitors include ceramic, polyester and mica. Issues that become more important at higher voltages that affect performance and reliability include capacitor construction (and how it affects the electric field), voltage coefficient, creepage distance along the surface, surge current capability (during an arc) and compatibility with potting compounds. See this list of high voltage capacitor manufacturers.

Thursday, October 25, 2007

High-voltage lab reopens today

The University of Waterloo's $5-million high voltage engineering laboratory (HVEL), which conducts advanced research and teaching for the power industry, will officially reopen this week, rising from the ashes of a major fire more than two years ago.

The HVEL lab does studies on such areas as power transmission and insulation.

"HVEL is one of the most research-intensive facilities in North America and features state-of-the-art technology," says Shesha Jayaram, director of the laboratory and a professor of E&CE. She says the electrical and power engineering researchers at UW bring together expertise in insulation, applied electrostatics, nanodielectrics (high voltage insulating materials with unique properties), pulse power applications, power electronics, renewable energy, power quality and distribution systems.

Alain Francq, director of industry and government relations for the E&CE department, adds: "Our strength is in our flexibility to go beyond standard testing, to produce innovative research and top engineering talent for the energy industry."

Wednesday, October 24, 2007

Bear Gets into High Voltage

The company, Bear Power Supplies, claims that its new BPS Series high-voltage DC-to-DC converters have up to five times better efficiency and ten times better load regulation than similar products on the market. The output range has recently been increased to 300V models.

Notable specifications:

Operating Temperature: -55 to +85C. No heatsink or electrical derating required.

Load regulation: 3% change from no load to full load (pretty good for a proportional converter)

Size: 0.5 x 0.5 x 0.4 inches (12.7 x 12.7 x 10.2 mm)

(Sorry for the headline...)


High Voltage DC-to-AC converter

If you are looking for a high-voltage +/-15kV ESD-protected DC/AC converter for driving electroluminescent lamps, be sure to see the Maxim MAX4990E. Output is 250Vac peak-to-peak:
  • Wide +2.4V to +5.5V Input Voltage Range
  • ESD-Protected EL Lamp Outputs:
    ±15kV Human Body Model
    ±4kV IEC 61000-4-2 Contact Discharge
    ±15kV IEC 61000-4-2 Air-Gap Discharge

For specifications see:

Monday, October 22, 2007

Another Plastic High Voltage Insulator

A PET thermoplastic polyester resin known as Rynite is being used in racing car ignitions. In that application , it must withstand high temperature, high vibration as well as being able to withstand the 50kV ignition voltage.

One grade of Rynite, FR946, is one such example. At 150°C, the dielectric strength grade is close to 90% of the room temperature rating.

Tuesday, October 16, 2007

Infrared Inspection

When working on high voltage products and power distribution systems, infrared inspection can sometimes prevent a major problem. Localized heating can occur due to corona or due to deteriorization of insulators. Sometimes even a small temperature rise can be indicative of a forthcoming breakdown, or a possible fire.

Friday, October 5, 2007

Protecting op amps against high voltage transients

Whenever high voltage is present in a system, arcs can cause damage through various mechanisms. One is to cause op amps in the system to fail.

Often, resistors, RC's, zeners, tranzorbs and the like are used. Here is another circuit protection technique to consider.

From the article referenced below,
"A reasonable approach disconnects the amplifier-output node from the output terminals for the period when the overload voltage exists on output terminals. "

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