Electrical Study for the Power Supply to QVC II from the KAHRAMAA network, Qatar

Within the Project scope, the load demand assessment is prepared for black out operation. The sum of maximum load demand for emergency condition was found to be 395 kW or 473 kVA. Load flow calculation results indicate that voltage profile at 6.6 kV and LV busbars are within the allowed limits that correspond to normal operating conditions. For black out topology and emergency service there are no overloaded elements in the network. Cable circuits are loaded 50%, or less, in comparison to their rated capacity. At the same time transformer units are loaded about 25%, or less. Short circuit calculations are performed with Power Plant SS 6.6 kV busbar section circuit breaker closed. At the same time circuit breaker at LV switchboard is assumed open (6.9/0.72 kV transformers at Power Plant SS not operate in parallel).

Based on the study performed, it is expected that maximum in-rush current for ET810101 transformer will not cause any unpleasant event in the service. That is confirmed also by comparison made between maximum in-rush current, and relevant expected three-phase short circuit fault current.

QVC System Model

This model is based on data presenting network equipment components that are installed in considered part of distribution network. The model is established in the form of common key single line diagram. It includes all modifications predicted by the scope of this project related to characteristic part of QVC distribution network.

Services provided

  • Carrying out a complete Load Flow Study, In-Rush Current, Fault Level & Protection Grading for ET810101 Power Plant step up Transformer 0.72/6.6kV 2MVA located at the power plant area. All that in order to identify the capability and capacity of the transformer under the study fed the new proposed admin building loads in case of long black outs.
  • The power and distribution system of 6.6/0.69kV SS is studied for normal power supply scheme and the short-circuit calculations are done for characteristic operation schemes that relate to this real system operation. The Relay Settings Co-ordination Study is performed for the three-phase and single-phase-to-earth faults.

Technical data

  • Load Flow, Fault Level and In-rush Current Study for step up Transformer 0.69/6.9kV 2MVA
  • Short Circuit Calculation


Qatar Vinyl Company (QVC), Qatar