ESMOGrid validation: Short Circuit Case 1

Short – circuit is an electrical system fault, when electrical path occurs within two or more conductive elements and, consequently, potential difference between them becomes close to zero. There are several types of short – circuits:

  • line – to – line short circuit, when conductive path occurs between line conductors (either two or more),
  • line – to – earth short circuit, when conductive path occurs between a line conductor and earthed neutral (the most common type of short – circuit).

Both of these conditions can be simulated with ESMOGrid Short – Circuit analysis module.

Short- circuit calculations are performed in accordance with IEC 60909 standard.

To calculate short circuit, you need to choose either SC max or SC min button (highlighted in blue in Fig.1) and choose one bus where you want to initiate short – circuit. If you choose SC max, ESMOGrid will calculate maximum short circuit current that is used for system elements sizing. SC min will give minimum short circuit current which is needed when setting protection devices sensitivity.

Fig. 1 One line diagram of analyzed network

Fig. 1 One line diagram of analyzed network

Short circuit calculations need to be precisely performed, in order to, avoid equipment failure or other damages. Therefore, we pay close attention to ESMOGrid Short – Circuit module calculations accuracy. In this article short – circuit results from ESMOGrid are compared to case example from IEC60909 part 4.

Analyzed system data is depicted in Table 1, short – circuit at Factory Bus results are in Table 2.

Table 1. Element parameters

Title Voltage level Resistance Reactance
System 33 kV 158.94 mΩ 1.5894 Ω
Lines from System to Bus 1 and Bus 2 33 kV 485 mΩ 485 mΩ
Transformers T1 and T2 6.3 kV 15.222 mΩ 380.234 mΩ
Motor 1 6 kV 149.26 mΩ 1.4926 Ω
Motor 2 6 kV 169.65 mΩ 1.6965Ω

 

Table 2. Fault branch current results comparison with reference

Location ESMOGrid Reference Difference
I, kA I, kA ΔI
From system 14.78 14.78 0.00%
From Motor 1 2.54 2.542 0.08%
From Motor 2 2.235 2.231 0.18%
At fault branch 19.541 19.55 0.05%

 

Calculation errors are less than 0.18%.

Reference

International standard IEC 60909-4, Short-circuit currents in three-phase A.C. systems, ch. 4, 2000.

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