Monday, June 28, 2010

High Voltage Laboratory Demonstration Video

The second largest High Voltage laboratory in the UK is located in the School of Electrical and Electronic Engineering, University of Manchester.  They have very high voltage ac and dc generators, which are used to test insulation systems.  Here's a video that showcases their high voltage capabilities.  It's worth a couple of minutes.

Thursday, June 24, 2010

Four-channel DC high-voltage measurement system up to 1 kV

There's a new four-channel high-voltage DC measurement system called “High Voltage Iso DAQ” for safely and reliably measuring voltage levels in high-voltage DC systems such as those employed in the battery circuits used in electric and hybrid vehicles. This test and measurement system from Ipetronic has four electrically isolated high-voltage dividers that, together with four external HV current limiters, cover a measurement range of up to ±1000 V. Acquired measurement results are digitized using a 16-bit ADC and made available directly on the CAN bus. After that, the data can be evaluated using a notebook/PC with DAQ software or a data logger.

The High-Voltage Iso DAQ’s signal scaling and measurement rate are configurable. The test and measurement system supports channel sampling rates of 1, 2, 5, 10, 20, 50, 100, 200, 500, 1000 and 2000 Hz, as well as a maximum overall sampling rate of 8000 Hz. The maximum permissible input voltage is 1000 V DC for CAT-I applications and 600 V AC for CAT-II applications at 50 Hz. Additional technical specifications include a test insulation voltage (2 s) of 3536 V AC and an input impedance of 21 MΩ//100 pF with the current limiter and HV cable. 

Wednesday, June 23, 2010

200kV Resistors

Wuerth Elektronik’s printed pulse resistors achieved the impossible high-voltage range of 200,000 V.  Yes, 200kV.  That has been realized by "smart-conductive polymer thick film systems". The company's printed pulse resistors’ reason of success is their capability for assimilating quite high KW-load required for milliseconds. In comparison with conventionally mounted resistors, the printed resistors’ primary advantage is the high integration potential and consequently reduced volume, resulting in more robust and cost-effective components.

In many cases, conventionally mounted components are available only as a wired version, resulting in complex assembly and not reliable solder joints. Wired pulse resistors are much larger than standard resistors, need a lot of space and enhanced production efforts, cause much higher costs for procurement and storage and keep the failure risk at the solder joint wire.

These printed pulse resistors can be even printed on a multilayer boards’ inner layer.  Printed resistors are without solder joint, consequently never affected by soldering defects. Standard resistors for pull up/down applications can be printed in a controlled process at a tolerance range of ± 30 %. For higher grade applications, the resistors tolerance is reduced to a range of ± 5 % over their entire life cycle, even under extreme climate conditions (40°C/92% rH /1000 h).

Monday, June 21, 2010

Silicone Grease

New lubricants improve safety around high voltage power cables

Silicone grease consists of two components. Pure silicone oil is mixed with a silica powder. The silica filler added to the oil makes it look like a grease but, in time, the oil starts migrating. It runs away and leaves the silica behind. What is left is no longer a lubricant, so the two rubber mating surfaces stick to each other and that makes it difficult to separate them.

The solution, Mashikian says, is to create a lubricant with a lower percentage of silica, or no silica at all. And that's what he and the staff at the Electrical Insulation Research Center have done. In fact, they've made five different lubricants which performed better than the commercially available silicone grease, he says.

"Studies of the new technology indicate the new lubricants will remain fluid," says Chuck Leuth, president of PolySi Technologies Inc., which has a license agreement with the University to commercialize the new technology.

For more information see , from which this is excerpted.

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