西门子资料专区

简介：
问题： 3WL断路器在通断变频器负载运行时会不会出现可以预见的不良效果？ 解答： 变频器产生谐波及伴随电缆而生的电压扰动，在线路供电中，干扰大多情况下为共模干扰。原因在于： - 由6脉冲供应引起的低频谐波。 - 在线路侧转换电抗器，引起高电压尖峰。 - 以极其快速的切换时间切换变频器的IGBT。 - 谐振电路造成高压峰值。 最重要的是在系统中应考虑EMC抑制的设计： - 金属机柜部分必须连接在一起并接地。 - 信号电缆和电源电缆必须分开布线。 - 始终使用屏蔽信号电缆。使用线性电抗器减少了低频谐波。 3WL断路器的电子式脱扣器ETU 只计算有效值，因此可适用于受谐波干扰的系统。而且ETU已通过基于EN 60947-2，Annex F标准的测试，包括电磁兼容性(EMC)测试，抗干扰测试及谐波测试。 需要注意变频器在IT系统中的应用。 在不接地的线路中，这些尖峰电流不能通过PE/PEN导体排出到大地。 对于3WL框架断路器通断变频器负载，尤其是在IT系统内，建议在ETU上附加一个EMC滤波器。这个滤波器连接在电流互感器和ETU之间来降低电压扰动。 订购：附加订货号Z=F31或单独使用订单号3WL9111-0AK32-0AA0。 条目号:23430857 日期:2006-06-29 QUESTION: Are there negative effects to be expected in the operation of 3WL with frequency converters? ANSWER: Frequency converters generate harmonics and often cable-born noise voltages, mostly common-mode interferences, in the line supply. Reasons are: - Low-frequency harmonics caused by 6-pulse supplies. - Switching reactors on the line side, causing high voltage peaks. - Switching the IGBT of the converter with very fast switching times. - Resonant circuits producing high voltage peaks. Most important is to have EMC-correct design of system configurations: - Metal cabinet parts must be connected together and must be grounded. - Signal cables and power cables must be routed separately. - Always use shielded signal cables. Low-frequency harmonics are reduced using line reactors. The electronic system of the ETU calculates the rms-value and is therefore suitable for systems being afflicted with harmonics. The ETU is tested according EN 60947-2, Annex F, including electromagnetic compatibility (EMC) tests, immunity tests and harmonics. Attention should be paid to the use of frequency converters in IT-systems. In non-grounded line supplies these peaks cannot discharge to earth via PE/PEN conductor. For ACBs switching frequency converters, especially in IT-systems, we suppose the use of an additional EMC-filter for the ETU. This filter is connected between CT and ETU and reduces noise voltages. Ordering: Order code Z=F31 or separately by using order-no. 3WL9111-0AK32-0AA0. Entry ID:23430857 Date:2006-05-31