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Relay Coordination Studies

In power system networks, protection has to be designed such that protective relays isolate the faulted portion of the network, to prevent equipment damage, injury to operators and to ensure minimum system disruption enabling continuity of service to healthy portion of the network.

Power system analysis is a very critical part in any electrical design and its operation. Relay coordination study or relay coordination calculation is a part of the traditional power system analysis performed for all plants and facilities for a smooth operation. Relay coordination studies plays a vital role in the electrical maintenance and plant operation.


Relay coordination is used to achieve proper fault identification and fault clearance sequence. These relays must be able to differentiate between the normal operating currents that including short time over currents that may appear due to certain equipment normal operation such as motor starting currents, Transformer inrush currents and sustained overcurrent due to fault conditions. power system relaying and overcurrent protection are mutually dependent concepts which contribute to the plants smooth operation. Protection coordination or protective device coordination study will include the protection relay setting calculation and the power system protection and switchgear, MCB, Fuse, ACB, VCB so on.

In order to provide the overcurrent protection we need to properly conduct the power system protection and the protective device coordination study with our compromising the electrical safety of the system. The main object of the protection coordination is to avoid nuisance tripping by proper protection relay setting calculation by enabling the power system protection. During fault conditions, these relays must operate quickly so as to isolate the faulted part of the network only and allowing for continued operation of the healthy circuits. Know More

Our Relay Coordination Study Methodology:

Our dedicated electrical professional team will visit your ream and collect all the data. For conducting a relay setting calculation we need all the electrical installation data of the plant and their complete behaviour manuals. Power system relaying is configured by the OEMs as a standard international practice and the manufactured will have a defined parameters with respect to the behaviour of the equipment. Once the data is collected we model the data collected in the reputed electrical simulation software ETAP /SKM. The data modelled will be integrated with the OEM library for setting the configuration values. The modelled network will be subject to various simulation studies like voltage drop analysis, short circuit studies and protective device coordination studies. The fault current calculation shall be done to identify what is the maximum available fault current at each and every feeder and bus. IEEE short circuit current calculation sheets will provide you the values of the 3 phase bolted and arcing fault. We have to use these short circuit calculation values obtained to perform relay coordination calculation. Relay setting calculation will depend on the fault current calculation and the time values.

  • Data Collection and SLD Preparation
  • Short Circuit Studies
  • Relay Coordination Studies
  • Implementation