IEEE 1584-2018 電弧閃絡計算步驟 (二)

  Step 9： Calculate the incident energy

1.        確定盤體尺寸修正係數。

2.        如果系統電壓為 600V < Voc ≤ 15000V，則使用公式（6）、公式（7）和公式（8）找到中間值。 利用公式(10)、(11)、(12)求電弧能量的最終值。

3.        如果系統電壓為 208V ≤ Voc ≤ 600V，則使用公式（9）確定最終電弧能量。

求中間值

(6)

(7)

         (8)

(9)

 where

E₆₀₀ is the incident energy at V_oc = 600 V (J/cm²)

E₂₇₀₀ is the incident energy at V_oc = 2700 V (J/cm²)

E₁₄₃₀₀ is the incident energy at V_oc = 14 300 V (J/cm²)

E_≤600 is the incident energy for V_oc ≤ 600 V (J/cm²)

T： the arc duration (ms)

G：the gap distance between conductors (electrodes) (mm)

I_{arc_600}： the rms arcing current for 600 V (kA)

I_{arc_2700}： the rms arcing current for 2700 V (kA)

I_{arc_14300}： the rms arcing current for 14 300 V (kA)

I_arc：rms arcing current for V_oc ≤ 600 V [using Equation (25)] (kA)

I_bf： bolted fault current for three-phase faults (symmetrical rms) (kA)

D： the distance between electrodes and calorimeters (working distance) (mm)

CF： correction factor for enclosure size (CF = 1 for VOA and HOA confi.)

lg： log₁₀

k1to k13： the coefficients provided in Table 4, Table 5, and Table 6.

Table 4 Coefficients for Equation (6), Equation (9), Equation (13), and Equation (16)

Table 5 Coefficients for Equation (7), Equation (14)

Table 6 Coefficients for Equation (8), Equation (15)

求最終值 (600 V < V_oc ≤ 15000 V)

                  (10)                (11)                  (12)

 where

E₁： the first E interpolation term between 600 V and 2700 V (J/cm²)

E₂： the second E interpolation term used when V_oc is > 2700 V (J/cm²)

E₃： the third E interpolation term used when V_oc is < 2700 V (J/cm²)

When 0.600 < V_oc ≤ 2.7, the final values of incident energy is given as follows：

E = E₃

When V_oc > 2.7, the final values of incident energy is given as follows：

E = E₂

求最終值 (V_oc ≤ 600 V)

電弧能量如下：

E = E_≤600

where

E_≤600： the incident energy for V_oc ≤ 600 V determined using Equation (9) solved            using the arc current determined from Equation (1) and Equation (5) (J/cm²)

E： the final incident energy at specified V_oc (J/cm²)

Step 10： 決定所有設備的電弧保護界線

1.    確定盤體尺寸修正係數

2.    如果系統電壓為 600V < Voc ≤ 15000V，則使用公式（13）、（14）及（15）來找出中     間值。 利用公式(17)、(18)、(19)求電弧保護界線的最終值。

3.    如果系統電壓為 208V ≤ Voc ≤ 600V，則使用公式（16）確定最終的電弧保護界線。

求中間值

(13)

(14)

 

(15)

(16)

where

AFB₆₀₀： the arc-flash boundary for V_oc = 600 V (mm)

AFB₂₇₀₀： the arc-flash boundary for V_oc = 2700 V (mm)

AFB₁₄₃₀₀： the arc-flash boundary for V_oc = 14 300 V (mm)

AFB_≤600： the arc-flash boundary for V_oc ≤ 600 V (mm)

G： the gap between electrodes (mm)

I_{arc_600}： the rms arcing current for 600 V (kA)

I_{arc_2700}： the rms arcing current for 2700 V (kA)

I_{arc_14300}： the rms arcing current for 14 300 V (kA)

I_arc： the rms arcing current for V_oc ≤ 600 V [obtained using Equation (5)] (kA)

I_bf： the bolted fault current for three-phase faults (symmetrical rms) (kA)

CF：the correction factor for enclosure size (CF=1 for VOA and HOA                                configurations)

T：the arc duration (ms)

lg： log₁₀

k1 to k13： are the coefficients provided in Table 4, Table 5, and Table 6.

求最終值 (600 V < V_oc ≤ 15000 V)

      (17)                                

       (18)

       (19)

 where

AFB₁： the first AFB interpolation term between 600 V and 2700 V (mm)

AFB₂： the second AFB interpolation term used when V_oc is > 2700 V (mm)

AFB₃： the third AFB interpolation term used when V_oc is < 2700 V (mm)

When 0.600 < V_oc ≤ 2.7, the final values of arc-flash boundary are as follows：

AFB = AFB₃

When V_oc > 2.7, the final values of arc-flash boundary are given as follows：

AFB = AFB₂

求最終值 (V_oc ≤ 600 V)

電弧保護界線如下：

AFB = AFB_≤600

where

AFB_≤600：arc-flash boundary for V_oc ≤ 600V determined using Equation(16) solved using the arc current determined from Equation (1) and Equation (5) (mm)

AFB：the final arc-flash boundary at specified V_oc (mm)

Step 11： 決定二次電弧電流

必須考慮電弧電流的變化，減少的電弧電流重複步驟 8、步驟 9 和步驟 10。其獲得的電弧能量和電弧保護界限之結果可能不同。 最終電弧能量或電弧保護界限是兩個計算值中較高的一個。

(20)

 where

VarC_f： the arcing current variation correction factor

I_arc：the final or intermediate rms arcing current(s) (kA) (see note)

I_{arc_min}： a second rms arcing current reduced based on the variation correction factor (kA)

V_oc： the open-circuit voltage between 0.208 kV and 15.0 kV

k1 to  k7： the coefficients provided in Table 7

Table 7 Coefficients for Equation (20)

NOTE—The correction factor (1 – (0.5 × VarC_f)) is applied as follows：

— 208 V ≤ V_oc ≤ 600 V： To I_arc (final current only)

— 600 V < V_oc ≤ 15000 V： To I_{arc_600}, I_{arc_2700}, and I_{arc_14300} (intermediate average arcing currents). The final I_arc value inherits the correction factor.

“0.5”係數表示應用平均電弧電流變化以求得電弧電流下限值。