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Arc-Flash Calculator

The purpose of this calculator is to help the plant engineer or electrician create a preliminary calculation of the reduction of Incident Energy (IE) by applying the PGR-8800 Arc-Flash Relay. All nameplate data should be collected by a qualified individual. The calculations below provide a typical-case scenario in 3-phase systems, as defined by IEEE 1584 calculations, and are for illustration purposes only. Actual values may vary.

Instructions

Please fill in the values in the green shaded boxes only. The values shaded in gray will calculate automatically.

  1. Select your Equipment Voltage
  2. Select your Equipment Class
  3. Indicate whether you know your Circuit Breaker (CB) Clearing Time number
  4. Indicate your Circuit Breaker(CB) Total Clearing Time
  5. Enter your Available Bolted Fault Current
  6. Enter your Incident Energy for Instantaneous

Note the New Incident Energy (NIE) Value — this is what your your Incident Energy will be by applying the PGR-8800 in your system.

Oops... the following errors were encountered:

1. Equipment Voltage
2. Equipment Class
3. Circuit Breaker (CB) Clearing Time
4. Calculate New CB Clearing Time (NCBCT)
ms
+
ms
=
ms
ms
ms
+
ms
=
ms
ms
ms
+
ms
=
ms
ms
ms
+
ms
=
ms
ms
5. Enter your Available Bolted Fault Current at the Load (SCC)
kA
kA
6. New Incident Energy (NIE) value WITH the PGR-8800 Arc Flash Relay
cal/cm2
%
%
%
7. Incident Energy with current protection
8. Enter Known Incident Energy (IE) with current protection
cal/cm2
 
cal/cm2
 
cal/cm2
 
cal/cm2
 
9. Percent Reduction in Incident Energy by applying PGR-8800
%
%
%
%
%
%
%

Note: Required fields are highlighted in green

1B. Transformer
2B. Data Collection

Please enter all of the known data. At a minimum, we need your Available bolted fault current (S3) at the Service if you don't have a transformer OR your transformer Size (T2), Secondary Voltage (T3) and Impedance (T5) to proceed with the calculations.

For T5. Impedance, please enter a percentage. It will be converted to a decimal value when performing the calculation. (Example: Entered 5.5% will be converted to 0.055).

If you know your Available Bolted Fault Current at the Load (SCC), hit the close button below and enter the value in Step 5 Short Circuit Current Value in the main window.

To calculate your Incident Energy value fill in the circuit breaker data below.

The required values are highlighted in green.

Service
Transformers
%
Circuit Breaker
* CB Mechanical clearing time, including tripping and clearing times.
65 5.4 5.4 3.1 3.1 3.0 -
55 4.6 4.6 2.7 2.7 2.5 -
45 3.8 3.8 2.2 2.2 2. -
35 2.9 2.9 1.7 1.7 1.5 8.1
30 - - - - - 7.0
25 2.1 2.1 1.2 1.2 1.1 5.8
20 - - - - - 4.6
15 1.2 1.2 0.8 0.8 0.6 3.5
10 0.8 0.8 0.5 0.5 0.4 2.3
7.5 0.6 0.6 0.4 0.4 0.3 1.8
5 - - - - - 1.2
 
65 10.8 10.8 6.2 6.2 6.0 -
55 9.2 9.2 5.3 5.3 5.0 -
45 7.5 7.5 4.4 4.4 4.0 -
35 5.8 5.8 3.4 3.4 3.1 16.2
30 - - - - - 13.9
25 4.2 4.2 2.4 2.4 2.2 11.6
20 - - - - - 0.3
15 2.5 2.5 1.4 1.4 1.3 7.0
10 1.7 1.7 1.0 1.0 0.8 4.7
7.5 1.3 1.3 0.8 0.8 0.6 3.5
5 - - - - - 2.3
 
65 16.2 16.2 9.3 9.3 8.9 -
55 13.7 13.7 8.0 8.0 7.4 -
45 11.3 11.3 6.5 6.5 6.0 -
35 8.7 8.7 5.1 5.1 4.6 24.3
30 - - - - - 20.9
25 6.2 6.2 3.7 3.7 3.2 17.4
20 - - - - - 13.9
15 3.8 3.8 2.3 2.3 1.9 10.4
10 2.5 2.5 1.5 1.5 1.2 7.0
7.5 1.9 1.9 1.1 1.1 0.9 5.3
5 - - - - - 3.5
 
65 62.2 41.1 12.4
55 52.9 34.9 10.6
45 43.5 28.7 8.7
35 34.1 22.5 6.8
25 24.6 16.2 4.9
15 14.9 9.9 3.0
10 10.1 6.6 2.0
7.5 7.6 5.0 1.5
 
65 107.9 71.2 21.6
55 91.3 60.3 18.3
45 74.8 49.4 15.0
35 58.2 38.4 11.6
25 41.7 27.5 8.3
15 25.0 16.5 5.0
10 16.7 11.0 3.3
7.5 12.6 8.3 2.5
 
65 59.3 39.1 11.9
55 49.6 32.8 9.9
45 10.1 26.5 8.0
35 30.7 20.3 6.1
25 21.5 14.2 4.3
15 12.5 8.2 2.5
10 8.1 5.4 1.6
7.5 6.0 3.9 1.2
 
35 162.2 107.0 32.4
30 139.0 91.7 27.8
25 115.8 76.5 23.2
20 92.7 61.2 18.5
15 69.5 45.9 13.9
10 46.3 30.6 9.3
7.5 34.8 22.9 7.0
5 23.2 15.3 4.6