IEC 61000-4-24-2015 pdf free download.Electromagnetic compatibility (EMC)- Part 4-24: Testing and measurement techniques – Test methods for protective devices for HEMP conducted disturbance.
4.5 Test fixtures
4.5.1 General
Test fixtures are mechanical setups with coaxial connectors on both the unprotected and the protected terminals. Their task is to hold the OUT. Two different types of test fixtures may be used. They are referred to as type A and type B as described below.
4.5.2 Type A fixtures
Gas discharge tubes intended to be used for protection of coaxial high-frequency applications may be tested in corresponding, commercially available holders. The protective device is inserted between the inner and outer conductor of the coaxial setup, with a minimum of influence on the characteristic impedance. Such holders allow the inherent properties of the device to be measured explicitly and with good repeatability.
4.5.3 Type B fixtures
4.5.3.1 General
Type B fixtures are universal and apply In principle to all kinds of two-terminal or two-port protective devices, whether they have a feed-through or non-feed-through configuration. However, measurements on low-voltage devices like protective diodes and varistors may be strongly influenced by inductive overshoot due to high dildi.
NOTE By ensuring the test fixture lead lengths are as short as practically possible, the risk of inductive influence can be mitigated
The fixture is composed of three parts: the unprotected shell, the partition screen and the protected shell (see Figure 2).
4.5.3.2 Unprotected shell
The dimensions and cross-section shape may be adapted to the size of the OUT. The shell may be cut into two parts in the axial direction for better access to the solder points. If not otherwise stated, the length of the wire from the unprotected connector (P1) to the input- contact of the OUT (P2) shall not be longer than the length of the current path in the OUT between points P2 and the grounding contact of the DUT (P3).
4.5.3.3 Partition screen
Feed-through protective devices shall be inserted in the partition screen in the same way as
in actual application.
Non-feed-through devices shall be passed through a hole in the partition screen as shown in Figure 2a) and 2b). The wire passing through the partition screen shall be Insulated. A feedthrough capacitor or other feed-through element shall not be used. A non-feed-through DUT may be placed close to the screen but shall not touch it, except if it is to be installed on to a metal wall in actual applications (as shown in Figure 2c)).
4.5.3.4 Protected shell
The protected shell serves as transition to the protected connector. The protected shell shall be made as short as possible. The length of the connection between point P2 and the protected connector shall be as short as possible.IEC 61000-4-24 pdf download.