Parameters of the pressure sensitive resistance and selection formula
Pressure sensitive voltage Voltage Varistor
As the name suggests, it is the threshold voltage that triggers the pressure sensitive resistance to reduce the impedance. This is generally a wide range.
Maximum continuous operating voltage Allowable Voltage Max
Is in a certain range below the pressure sensitive voltage, can ensure that the work voltage with a high impedance representation. Generally lower than the lower limit of the pressure sensitive voltage to a certain value.
Maximum peak voltage Clamping Voltage Max
As the name suggests, is beyond the scope of this voltage is beyond the reasonable scope of work, at this time, the device will face the risk of damage, the voltage is reduced after the may not be restored.
Voltage 242-279, is the voltage at both ends of the pressure sensitive resistance in the range of value, pressure sensitive resistance to start action, the input voltage of the clamp. However, this work voltage belongs to transient spike voltage. Under normal circumstances, the pressure sensitive resistance is connected to the input wire port, then, it will be at both ends of the duration of the circuit operating voltage. This voltage value is persistent. Is not more than 175V. (AC) defined by valid value. Voltage Max.Clamping, refers to the pressure sensitive resistance of the largest clamping voltage. Household AC port general with 471K pressure sensitive resistance. The effective value of household AC power is 220, the peak value of up to 380, so at least 400, leaving a margin, choose to choose 471, in the pressure of the pressure sensitive resistance is expressed as 471V.
The varistor voltage using a formula: 220 (input AC voltage) *1.414 (peak coefficient) 1.5 (safety coefficient) =466V PRG 470V=471, the highest voltage of the varistor is 470v, as long as the upside down directly in 1.414=332V. This figure is AC power shall not be higher than 332V, or breakdown. When the real surge hit, 220 to 332 has no much difference, so this model is popular.