Industrial Power System Audit & Protection Analysis

Outline

In 2020, Power Control Engineers was engaged by a large Australian meat processing and distribution company to conduct a detailed power system audit and modernise the electrical documentation for their Tamworth Site; with the aim of improving functional efficiency and electrical safety. The site comprised of both high voltage and low voltage reticulation, with 5 transformers respectively supplying large low voltage systems.

Upon completion of the power system audit, and development of a new electrical drawing set for the site, the client further partnered with PCE to implement a protection study on the existing HV/LV electrical infrastructure. Power Control Engineers were able to deliver a highly refined and optimised HV/LV protection scheme, maximizing operational efficiency and enhancing safety.

Power System Audit & Documentation Modernisation

A power system audit on an industrial site is typically motivated by the desire to improve electrical safety, namely minimising risks to site personnel and electrical equipment. With this motivation, as well as the recent implementation of multiple low voltage upgrade projects, the client opted to leverage the power system expertise of Power Control Engineers and provide further clarity on their private network.

PCE attended site for multiple days to conduct an audit of the HV and LV network, gathering the foundational data of the project. The on-site audit works included visual inspection of approximately 140 low voltage distribution boards and MCC’s. Electrical panels were meticulously documented, with consideration of equipment specification, asset identification, protection settings and circuit configuration.

The client was provided with a detailed standardised drawing set for the HV/LV distribution network, improving efficiency and safety for site electrical personnel during operation, isolation, network expansion and planning. 

Figure 1 - Network Diagram Excerpt

To complement the site documentation, a site wide IEC60909 short circuit study was conducted, for the high voltage and low voltage systems. These works included utility liaison and further on-site visual inspection, providing the client with a detailed representation of prospective fault current throughout the facility.

Upon project completion, the results of the audit were presented in the comprehensive drawing package, giving the client confidence in their operating network, the equipment in use, the power system layout and clarity around electrical risk.

Figure 2 - Single Line Diagram Excerpt

Protection Coordination Study

The next stage of the project saw PCE conduct a protection study on the site, to determine suitability of existing protection coordination and protection functionality.

PCE liaised with the supply authority, Essential Energy (EE), to conduct high voltage analysis from the upstream EE automatic circuit recloser, to the high voltage transformer protection relays. Utility coordination and transformer overload/short circuit protection was optimised in multiple locations. One notable recommendation saw the correction of a suboptimal overcurrent function on one of the five 11/0.433kV transformers. This observation, and associated remedial action, vastly reduced the risk of large equipment damage and prolonged operational outages.

Protection analysis was further conducted on the low voltage network, involving assessment of approximately 150 protective devices. Restorative methods were provided for low voltage cable protection and device coordination, mitigating the risk of cable damage and nuisance tripping.

Through implementation of a site-wide protection study, the client was able to reduce the probability of electric shock, equipment damage and prolonged outage – without the complexity.

Figure 3 - Protection Coordination Study Excerpt