**AC 15 test system**

We started commissioning work as soon as the updated AC15 test equipment arrived. Until now, most test parameter are qualified, except for (U=250V, I=150A, cosφ=0,3) and (U=255V, I=165A, cosφ=0,3), the parameters around this range are also unstable. We tried several methods to solve the problem including use conducting paste in contact points, increase the wire cross-section area and minimize connection length, however, the effect of all these actions are not obvious.

The wire cross-section of test reactor is 14 square mm, and total inductance of each reactor is about 19 mH, which means about 5.97Ω in50Hz circuit, meanwhile, with a length of about 36m, the DC resistance of one reactor is less than 0.5Ω, and the inherent power factor of the reactor shall be less than 0.1, which meets the test requirement well. However, the actual inherent power factor of reactor is about 0.2, and there is a deviation from theory to practice. Meanwhile, the actual circuit inherent resistance is 0.68Ω in 250V-150A test, which shall be decreased to 0.51Ω if we want to generate 0.3 power factor.

As we’ve tried possible solutions to minimize circuit resistance, the only possible problem is the inherent power factor of rector is higher than expect, which cause the higher entire circuit power factor. If we want to strictly meet the test parameters, all reactor shall be redesigned and manufactured with a larger cross-section (at least 2 times of current one) with larger volume. Which is inconstant with test room space and mobility requirement.

Besides, in IEC standards, when it requires 1,1 times Ue, there is no mandatory requirement of 1.1 times Ie, which means (U=255V, I=165A, cosφ=0,3) parameter is not a mandatory requirement. Thus there is only one parameter (U=250V, I=150A, cosφ=0,3) does not meet original RS document.

In early technical discussion, this AC15 test equipment is mainly designed and manufactured for 10A current class (10 times 100A)，but considering research & development requirement, the RS document expanded test current to 5A-15A. The design of this requirement is also based on 10A with some extension to meet a wide range, we also developed reactor winding method to meet the mobility requirement.

Therefore, if the last parameter is vital, we would like to try another design, but the test room space and mobility shall also be considered, otherwise may we discuss the necessity of this parameter.

**DC13 test system**

We winded the reactor strictly according to appendix B of IEC60947-5-1, but the inherent resistance is too large to generate test current (there is no suggestion for DC24V, 15A in appendix B), thus we tried to increase wire cross-section, and use several reactors for serial and parallel connections, but neither way worked. With our experience and similar reactor producer’s experience, there is no better solutions. We’d like to develop the reactor if there is better experiences in Germany.

Another possible way is to use electronic load, with soft-start function, it may generate the current and characteristic time, the only obstacle is there is no recommendation of forbidden in IEC regulation. We’d like to try electronic load for research purpose and provide voltage & current waves if there is no objection. This work may take about two to three weeks. If the voltage & current meet the test requirements, may we discuss to replace current test load with electronic one.