KANAGAWA, Japan, April 15, 2009 - OKI Electric Cable (TSE: 5815) together with Tokyo Metropolitan University, today announced that they have succeeded in developing a new method (patent pending) to suppress micro-surge, an over-voltage noise that occurs instantaneously caused by inverter switching signals. OKI Electric Cable's new method employs a surge suppression cable and a newly developed energy regeneration module. These new technologies enabled the company to develop the world's first ultra small micro-surge suppressor, the "eco Surge™ µ(micro)."

"We are very excited about this revolutionary method that enabled us to make the micro-surge suppressor ultra small. The surge suppression wire technology and the energy regeneration module, which includes a delay circuit and a rectifier circuit, are based on OKI Electric Cable's advanced technology for designing noise-resistant cables, and on the studies of Professor Toshihisa Shimizu at Tokyo Metropolitan University," said Takashi Hattori, President of OKI Electric Cable. "We believe we can apply this method not only to surge suppressors but also as to other noise countermeasures."

Compared to the conventional method, which employs electric filters, this new suppressor reduces power consumption to a minimum (lower than one-thirtieth), and size to less than one-eightieth*1 with 15KW power motors. In addition, more than 90% of the micro-surge noise can be suppressed. Sales of "eco Surge µ(micro)" are planned to start in July 2009 worldwide. OKI Electric Cable will showcase this suppressor at TECHNO-FRONTIER 2009 (EMC Japan 2009), which will be held from April 15-17 at Makuhari Messe in Japan. (Booth number: 5421)

As machine tools become higher in precision and faster to operate, the speed of inverter switching is also becoming faster. In addition, by applying higher power voltage to improve power efficiency, micro-surge, which is induced by impedance*2 mismatch, also increases. This can cause malfunctions in the peripheral circuits and have adverse effects on inverter-fed motors. Such effects include insulation deterioration in motor coils, which damages the motor.

For these countermeasures, conventionally, LC filter circuit had been inserted between the inverter and drive-wire that slows down the surge rise on drive signal waveform and dissipates the surge energy as heat. However, with this method, as the motor power increased, it was necessary to use expensive and large sized high-power-rated capacitors and coils. Thus, the space requirement, price and increased power consumption for suppression had been problems.

OKI Electric Cable had developed a surge suppressor based on surge suppression cable and energy regeneration technology which was significantly smaller in size than conventional filters. To reduce the size even more, OKI Electric Cable jointly developed this new suppressor with Tokyo Metropolitan University. By efficiently returning only the surge energy to the inverter input, the two groups succeeded in developing a surge suppression method with minimal (less than one-thirtieth compared to conventional filters*3) power consumption for suppression*4.

This new method does not require high-power-rated capacitors or coils. The "eco Surge µ(micro)" consumes less power to suppress surges, thus less heat is generated. By adjusting the delay-circuit constants of the energy regeneration module, more than 90% of the micro surge noise can be suppressed and reused as power.

The "eco Surge µ(micro)" can be placed in areas where conventionally it could not due to limited space in the switchboard. In addition, it can be used in a wide range of applications such as energy savings for inverter-fed motors.

Going forward, OKI Electric Cable will enhance its noise-resistant products and focus on developing leading-edge technologies to respond to a broad range of customer needs.

Glossary

• *1:Size reduced to 1/80
  Size compared to former filters
  - Former filter size: 30cm x 30cm x 33cm=29700(cm³)
  - eco surge µ: 10cm x 9cm x 4cm=360(cm³)
  - Size ratio, former to eco surge µ: 29700/360=82.5
  - Comparison to conventional filters: 1/(26.2) x 3)=1/82.5

• * OKI Electric Cable's surge suppressor size:
  - For 50m: "SSU50 TA-NS(W)140 x (L)230 x (D)244(mm)
  - For 100m: "SSU100 TA-NS(W)202 x (L)281 x (D)394(mm)

• *2:Impedance: This is the amount of electrical resistance for AC signal. The impedance value is determined with R(resistance), L(inductance) and C(capacitance).
• *3:Compared to conventional filters:

Reference

Characteristics

With the delay circuit and the rectifier circuit, the suppressor offers a method to recover surge energy, thus, it can achieve the following:

1. Surge control measures are achieved with minimal power loss
2. Size is reduced to less than one-eightieth and power used for suppression to less than one-thirtieth (at 15kw), compared to general filter methods
3. Surge suppression rate is over 90%

Example of application

• Power: 100kw Max.
• Rated temperature and power: 105°C, 600V
• Safety standard: UL

Size

At 15Kw

• Size: 100x90x40mm
• Weight: 300g

This product eliminates the use of the six substances listed in the RoHS (Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment) Diective in Europe.

Sales

• Starts July 2009

Sales plan

• 2009: 100 million yen
• 2010: 500 million yen

About Oki Electric Cable Co., Ltd.

Established in 1936, Oki Electric Cable Co., Ltd. provides various advanced communications cables, optical cables, and related electronic parts and equipment to the worldwide market. As a member of the OKI Group, Oki Electric Cable Co., Ltd. plays a major role in the group, with the sales of more than 13 billion yen. For more information, please visit the Oki Electric Cable website at http://www.okidensen.co.jp/en/

Suppressing µ surge ⌈eco Surge ™ series⌋

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