CHAPTER 3: INSTALLATION WIRINGC60 BREAKER PROTECTION SYSTEM – INSTRUCTION MANUAL 3-273Figure 3-24: Contact input connected to a contact output with resistor (R2) across the inputApplication exampleThis example is for illustrative purposes only and the calculations present the worst-case scenario. In practice, the value ofdebounce time can be lower.Contact input ON state impedance used in the calculation of the discharge period is based on the following table.Table 3-4: Discharge periodDebounce time setting = 2 msAssume a stray capacitance of 0.1 μF.Assume an initial voltage across the stray capacitance "Vinitial" = 19 V (Vthreshold - 65 V), where Vthreshold = 84 V. Theinitial voltage Vinitial depends on values of impedance of R1 and contact inputs when the contact input is OFF (non-activated state).Therefore, discharge time constant (τ) =50 kΩ *0.1 μF = 5 ms.Discharge period t is calculated from the following equation:Vthreshold = (Vbatt - VInitial) *e^ (-t/τ)84 = -149 *e^ (t/0.005) Eq. 3-1T = -0.005 * ln (84/149) = 0.0029 sTherefore, in this example the contact inputs operate.To prevent this operation, the debounce time must be increased to 4 ms (set debounce time as per the following table) orinsert a resistor less than or equal to "R" as calculated later.Table 3-5: Typical debounce time settingBattery voltage (V) Input impedance (kΩ)130 50250 97Stray capacitance (μF) Battery voltage (V) Debounce time (ms)0.05 130 20.1 130 40.2 130 60.05 250 3
