Selection and precautions High Performance Varistor

Selection of High Performance Varistor before, you should know the following relevant technical parameters: Nominal voltage is at a predetermined temperature and direct current flow, voltage across the varistor efficient. Leakage current is at 25 ℃, when the application of the maximum continuous DC voltage, high varistor flowing current. Voltage rating refers Glass Coating varistors ating current pulses through 8/20 presented at both ends voltage peaks. Through traffic is applying a predetermined peak current pulse current (8 / 20μs) waveform when. Surge environmental parameters include a maximum inrush current Ipm (or the maximum surge voltage and surge Vpm source impedance Zo), surge pulse width Tt, two adjacent surge minimum interval Tm and the High Performance Varistor predetermined operating lifetime, the total number of surge pulses N and the like.

Generally, metal oxide varistor function often with the protection device or devices in parallel, under normal circumstances, High Performance Varistors across the DC or AC voltage should be lower than the nominal voltage, even when the power fluctuations at worst should not be selected higher than the rated maximum continuous operating voltage, the maximum continuous operating voltage value corresponding to a nominal voltage value is the choice of values. Overvoltage protection areas for the application, the varistor voltage value should be greater than the voltage value of the actual circuit, the general should be selected using the following formula: VmA = av / bc where:

a circuit for the voltage fluctuation coefficient; v DC operating voltage for the circuit (when ac rms); b for the varistor voltage error; c to component aging coefficients,; VmA actual value thus calculated is 1.5 times the operating voltage of the DC In exchange the state should also consider the peak, and therefore the results should be expanded to 1.414 times.