MIL-STD-461G CS109: Conducted Susceptibility, Structure Current

MIL-STD-461G CS109 applies from 60 Hz to 100 kHz for equipment and subsystems that have an operating frequency of 100 kHz or less and an operating sensitivity of 1 μV or better (such as 0.5 μV). Handheld equipment is exempt from MIL-STD-461G CS109. 

According to MIL-STD-461G CS109, the EUT shall not exhibit any malfunction, degradation of performance, or deviation from specified indications, beyond the tolerances indicated in the individual equipment or subsystem specification.
 

Test Equipment

The test equipment shall be as follows:

• Signal generator
• Amplifier (if required)
• Isolation transformers
• Current probe
• Measurement receiver
• Resistor, 0.5 ohm
• Coupling transformer

 

Procedures

The test procedures shall be as follows:

• a. Turn on the EUT and measurement equipment and allow sufficient time for stabilization.
• b. Set the signal generator to the lowest required frequency. Adjust the signal generator to the required level as a minimum. Monitor the current with the current probe and measurement receiver.
• c. Scan the signal generator over the required frequency range in accordance with Table III while maintaining the current level at least to the level specified in the applicable limit. Monitor the EUT for susceptibility.
• d. If susceptibility is noted, determine the threshold level in accordance with 4.3.10.4.3.
• e. Repeat 5.11.3.4b through 5.11.3.4d for each diagonal set of test points on each surface of the EUT to be tested.

 

Test Setup

The test setup shall be as follows:

• a. It is not necessary to maintain the basic test setup for the EUT as shown and described in Figures 2 through 5 and in 4.3.8.
• b. Calibration. No special calibration is required.
• c. EUT testing.
  • (1) As shown in Figure CS109-2, configure the EUT and the test equipment (including the test signal source, the test current measurement equipment, and the equipment required for operating the EUT or measuring performance degradation) to establish a single-point ground for the test setup using the EUT ground terminal.
    • (a) Using isolation transformers, isolate all AC power sources. For DC power, isolation transformers are not applicable.
    • (b) Disconnect the safety ground leads of all input power cables.
    • (c) Place the EUT and the test equipment on non-conductive surfaces to enable a single point ground to be established.
  • (2) The test points for the injected currents shall be as follows: 
    • (a) Equipment that will not be rack-mounted: At diagonal extremes across only the mounting surface.
    • (b) Rack-mounted equipment: At diagonal extremes across all surfaces of the equipment.
    • (c) Deck resting equipment: At diagonal extremes across all surfaces of the equipment.
    • (d) Bulkhead mounted equipment: At diagonal extremes across the rear surface of the equipment.
    • (e) Cables (all mounting methods): Between cable armor, which is terminated at the EUT, and the single point ground established for the test setup. This requirement shall also apply to cable shields and conduit unless they have a single point ground.
  • (3) Connect the signal generator and resistor to a selected set of test points. Attachment to the test points shall be by conductors that are perpendicular to the test surface for a length of at least 50 cm.

FIGURE CS109-1. CS109 limit





FIGURE CS109-2. Test configuration




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