Roseburg, Ore. Caddock Electronics Inc. has introduced a series of Type VMR transient tolerant voltage monitoring resistors for industrial and commercial power quality and power metering applications. The non-inductive devices are said to maintain excellent precision and stability when exposed to severe electrical transient abuse (overloads and impulses) and extreme environmental conditions.
The new precision voltage monitoring resistors are available in resistance values from 500 KΩ to 10 MΩ with an absolute tolerance of 0.1% to 1%. Tighter tolerances are available. The operating voltage ratings range from 250 VACrms to 2000 VACrms. It also provides a temperature coefficient of 25 ppm/°C or 50 ppm/°C and is available with TC ratings as tight as 5 ppm/°C.
Designed for use in voltage measurement circuits in power quality meters, kilowatt-hour meters, power and energy measurement equipment as well as other applications that require precision monitoring of electrical service voltages, these VMR resistors can be optimized to handle transient impulses up to 15 kV (electrical power system transient waveform 1.5/50 microseconds).
The company said to achieve the long term stability and excellent transient capability the new devices use the company's Tetrinox low TC, resistance film system in combination with its ceramic "sandwich" construction, which also provides long-term stability in applications with extreme humidity exposure.
Typical pricing for these semi-custom devices is $2.00 to $3.00, in quantities of 10,000, depending on resistance value, tolerance, TC, and transient capability. Engineering evaluation samples are available in six weeks.
Caddock Electronics, Inc., 1-541-496-0700; www.caddock.com