In the selection plc cpu modules, we are most concerned about the selection of filters, six major reason in the selection process, we want to know. Feedthrough filter, it must be determined according to the size of the space, and installation methods filter shape structure, installation size, then according to the voltage level of electrical current size selection filter parameters. Furthermore, we should note the following points to be found to meet your needs using the feedthrough filter. First, the circuit forms
According to the principle of impedance mismatch, filter impedance and impedance mismatch on both sides of the larger ports, the energy of electromagnetic interference attenuation is more effective, considering the low end of the high-impedance termination impedance circuit filter selection filter should be in, Principles high impedance, low impedance end of the
digital output module filter circuit is terminated, and the selection of the filter circuit according to the filtering requirements of the form. Second, the feedthrough filter insertion loss filter parameters most important parameter is the insertion loss, plc cpu modules which reflects the filter for suppression of interference signals. Various EMI filters have their corresponding attenuation versus frequency curve, plc cpu modules when selecting filter insertion loss should be determined based on the frequency and the extent and the cutoff frequency of the signal to interference attenuation requirements, it is worth noting that factory to the insertion loss are no systems in 50 European load (load> data measured under the conditions, but in the actual circuit input / output impedance is 50 ohm just not so practical in the line filter insertion loss and products often have different nominal values. for measuring filter performance, in the application and also the approximate measurement line l measurement, this is done in order to more realistic three feedthrough filter feedthrough filter cutoff frequency cutoff frequency 3dB insertion loss of the filter is called the frequency when the frequency exceeds the cutoff frequency of the stopband filter to enter the area, resistance to electromagnetic interference band signal attenuation will be greater in order to ensure the required pass frequency signals, unnecessary frequency signal is suppressed, must select the cutoff frequency of the filter well. to the filtering of a signal should be 10 times higher than the
micro smart plc frequency of the operation start signal at a frequency filtering, for example Noise data lines a 5MHZ, the cutoff frequency of the filter to be similar to 50MHZ, so as to make noise attenuation does not affect the signal. Generally, the lower the cutoff frequency of the filter, the greater the size, the price is higher, So do not blindly choose the filter cutoff frequency is too low, or the signals will need to filter out four, working electrical feedthrough filter operating voltage feedthrough filter when the filter is working properly within the operating temperature range can long withstand voltage. Moreover also need the correct choice of AC and DC filters, can not substitute
plc programmable controller each other, especially in applications where AC DC filter will not allow the use of alternative, otherwise the filter will fail and even damage due to almost all of the electromagnetic compatibility The project has a pulse interference tests, to be considered in the selection of the filter effect of this high-voltage pulse interference, voltage or resistance voltage to leave a margin in the high-voltage, high-current DC workplace, common organic film material feedthrough filter.
