Electromagnetic compatibility (EMC) has recently become an international concern as interference from frequencies emitted by electronic and electrical equipment may hamper the proper functioning of devices. For instance, when affecting life-sustaining pacemakers or aircraft instruments, such interferences can be become real hazards and threaten the life and safety of the public. To safeguard such impact, many countries have introduced EMC controls and regulations. Manufacturers who wish to export electronic or electrical products to these markets would have to demonstrate that their products meet the necessary requirements specified by the authorities.
Thus, the Thai Industrial Standards Institute (TISI) has erected the first EMC laboratory which has the capability of performing both electromagnetic interference (EMI) and electromagnetic susceptibility (EMS) testing in Thailand. The EMC laboratory will provide the necessary testing services to Thai electrical and electronic industries to enable their products meeting the essential requirements of the major civil EMC regulatory bodies worldwide. The laboratory is scheduled to commence its services in September 1998.
The EMC laboratory is part of the Electrical & Electronic Testing Laboratory under TISI Testing Centre, located in Bangpoo Industrial Estate, Samutprakarn province, 30 kilometers southeast of Bangkok. The major facilities consist of a 1 0-metre Semi Anechoic Chamber (SAC), a Compact Diagnostic Chamber (CDC), a Radio Frequency (RF) Shielded Chamber, a control room with automated testing system and an amplifier room.
The Semi Anechoic Chamber is capable of meeting the specific requirements of a 10-metre range radiated emissions testing. At frequencies from 30 MHz to 18 GHz, the site attenuation of the chamber will be within + 4 dB of theoretical normalized site attenuation (NSA) as required by ANSI C63.4. The chamber also has a raised floor to allow all interconnecting cables between an Equipment Under Test (EUT) and any exercising equipment (if required) to be run under the ground plane to ensure minimal effect on the test.
Moreover, the Semi Anechoic Chamber and the Compact Diagnostic Chamber are both equipped with appropriate amplifiers and signal generators to provide the required field strength and signal modulation to meet the requirement of radiated immunity testing defined in IEC 1000-4-3. These chambers, placed with series of portable prefabricated ferrite tile absorber panels over the specular floor area, will be independently calibrated to ensure the required field uniformity. All EUTs will be monitored during testing by a fiber optically controlled video camera system. The shielded enclosures of the chambers will provide shielding effectiveness of at least 1 00 dB across the measurement spectrum.
In addition to the SAC and CDC, the RF Shielded Chamber has been installed and will be utilized for testing of conducted emissions, conducted immunity, electrostatic discharge (ESD), electrical fast transient (EFT), surge, line interference, magnetic field, hormonic currents and voltage fluctuation.
