Emi emc test1/15/2024 The discussions brought forth some concerns that the applied signal level would be different depending on which of the two primary monitoring methods (returning to the signal generator calibration settings or returning to the amplifier output calibration voltage) were used and that the risk of a significant over-test would damage the EUT if the calibration monitoring was omitted during test.Īs indicated earlier, using the signal generator setting would omit changes or adjustments of the amplifier that could affect the applied voltage. However, this can also result in applying excessive voltage if the characteristic impedance is high or excessive current if the impedance is low. To simplify the process of measuring a relatively low-level interfering signal near the power frequency, some laboratories, in the interest of automating the testing, establish software that simply applies the calibrated voltage setting without regard to the voltage applied to the EUT, which is called “playing back the calibration setting.” This eliminates the need for feedback measurements to serve two control points and meets the requirement of applying “at least” the required signal level. The setting is monitored in conjunction with the applied voltage at the EUT to maintain the required test level. The majority of test facilities involved in the discussion used the either the signal generator output setting or the measured voltage at the amplifier output recorded during a pre-test calibration. This procedure calls for monitoring two levels of the applied (test voltage applied and calibrated power) signal and controlling the signal source setting to maintain the applied signal to the lesser of test voltage or calibrated power. While maintaining at least the required signal level, scan the required frequency range while monitoring the EUT for susceptibility. (From paragraph 5.72 of MIL-STD-461G-the requirement is met when the power source is adjusted to dissipate the power level as shown on Figure CS101-2 ( Figure 2 herein) in a 0.5-Ω load and the Equipment Under Test (EUT) is not susceptible.)ĭ. On the other hand, power is limited to the level calibrated. The test voltage limits are presented in Figure 4 for all devices. Increase the applied signal amplitude until the required voltage or power level is reached on the power lead. Set the signal generator to lowest test frequency.Ĭ. Establish operation in the test configuration.ī. MIL-STD-461G specifies a testing configuration as shown in Figure 3. This adjustment need often prompts the use of the amplifier output voltage as the setting to allow gain adjustment and maintain the control setting.įigure 1: CS101 Basic Calibration Configurationįigure 2: Calibration Power w/Voltage Terms The range of calibration power through the frequency range often calls for amplifier gain adjustment to maintain operation in the linear region, depending on the amplifier performance. One could easily use the signal generator amplitude readout as the setting if the amplifier gain remains stable or does not require adjustment. The open issue is what defines the signal source. Scan the required frequency range for testing and record the signal source setting needed to maintain the required power level. Record the setting of the signal source.ĭ. Increase the applied signal amplitude until the oscilloscope indicates the voltage level corresponding to the maximum required power level specified for the limit as shown in Figure 2. Set the signal generator to the lowest test frequencyī. MIL-STD-461G specifies a calibration configuration as shown in Figure 1. MIL-STD-461G Procedure 2.1 CS101 Calibration This review examines test procedures used to accomplish the testing and identifies variances encountered along with considering alternate methods that may be used to meet the goal of the test standard.Ģ. The standard calls applying a test voltage level but allows for the requirement to be met if the interfering signal power source is adjusted to dissipate the power curve in a 0.5-Ω load. Murat Celep, TUBITAK UME, ĭiscussions with various members of the electromagnetic compatibility (EMC) community that deal with MIL-STD-461 testing revealed that various methods were being used to limit the applied power in CS101 testing. Steve Ferguson, Compliance Direction LLC, MIL-STD-461 CS101 Test Method Review Authored By:
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