New Magnetic Field Coil Generates Fields Up To 1200 A/m

Teseq Inc., a developer and provider of instrumentation and systems for EMC emission and immunity testing, offers a new magnetic field coil that generates fields up to 1200 A/m during magnetic field testing.  The INA 703 is designed for testing to IEC 61000-4-8 (supply frequency magnetic fields), IEC 61000-4-9 (pulsed magnetic fields) and IEC 61000-4-10 (oscillatory magnetic fields) standards.  It is well suited for medical equipment, military, avionics, aerospace and industry applications.

By using a multi-turn (37 turn) configuration, the INA 703 is able to generate higher field levels of up to 1000 A/m using a programmable power source rated for >/- 30 A like the ProfLine Conducted Immunity Test Systems. This enables testing with a current THD (total harmonic distortion) of <8 percent, as required by IEC 61000-4-8, that can only be met with a low distortion sine wave from a programmable AC source.

Another advantage of using a programmable power source is that various supply frequencies can be tested, not only 50 Hz and 60 Hz as requested by IEC 61000-4-8, but also DC and 16.7 Hz as required by some railway standards (EN 50121-4). Together with a TESEQ NSG 1007 source, INA 703 is able to generate fields with frequencies from DC to 400 Hz in 0.1 Hz resolution steps.

Taps at turns one and five provide increased accuracy when generating low amplitude fields.  The required coil drive voltage is increased by reducing the turns ratio of the coil.  This establishes a suitable input voltage range that allows good regulation of the test level amplitude. The tap off at one turn is primarily used for testing to IEC 61000-4-9 and IEC 61000-4-10, since both standards only require a single turn coil.

For testing to IEC 61000-4-9, the INA 703 can be used with any classic combination wave generator, including Teseq’s NSG 3040 or NSG 3060 along with the INA 752 pulse wave shape adapter.  When connected to an appropriate slow oscillatory wave generator, the INA 703 enables testing to IEC 61000-4-10.   The INA 703 is also well suited for use with MFO 6501 or 6502 current sources and Teseq’s NSG 3000 series generators to generate mains frequency fields up to 120 A/m continuously and short term (three seconds), both at 50 Hz and 60 Hz.  With its U-shaped rigid aluminum base and wheels, the INA 703 is quickly positioned next to or around the EUT.  The coil size is 1 by 1 m and has a homogeneous field volume of 60 by 60 by 50 cm.

The INA 703 has a maximum continuous supply frequency current of 10 A, a maximum short term supply frequency current of 35 A for three seconds, a maximum continuous supply frequency field strength of 330 A/m and a maximum short term supply frequency field strength of 1100 A/m for three seconds.  The unit has a maximum pulsed current of 1500 A (8/20 µs wave) and a maximum pulsed field strength of 1200 A/m.