There is a number of large installations that do not quite fit the labels considered before in this publication. Industrial locations, medical complexes, shopping centres and other large objects generally have their own step-down transformer and parts of installation at medium voltage. There are therefore also numerous other methods applicable to this voltage range that are not specific to any particular plant. This solution set will deal with such methods and their applications. Most of them can be used in previously considered locations and scenarios.
Lightning protection and surge protection devices need to be considered as a whole in the medium voltage range. They, of course, strongly depend on the location’s specifics and how the earthing system has been executed.
Methods for measuring partial earthing integrity with a single clamp deserves consideration. There is the general overview of testing switches, joints, bus bars and other low-resistance elements.
Step method for insulation resistance is a generally useful method in cases of very high nominal voltages – it can reveal issues at lower test voltage than the working one.
Industrial locations need to confirm the insulation and bonding of walls and floors. Specific electrodes and methods are necessary.
Power quality analysis can save a lot of energy and hence money and is therefore popular in industrial and other professional settings. Asymmetry is amongst the most destructive preventable power quality issues.
Switching events cause considerable disruption of power quality in high voltage installation and the rest of the network. They must be monitored and controlled.
Before starting a construction project, the electrical properties of the locality need to be determined. Specific earth resistance measurement is required for planning the grounding electrodes.
Different measurement frequencies are used in the measurements to gain a full understanding of its properties under extreme circumstances such as lightning strikes.
Industrial locations need more powerful protection than standard RCDs allow, called an ELR or earth leakage relay. Its working principle is a bit different and safety can be compromised in certain circumstances, but ability to protect high powered systems is the primary concern.
For rapid fault-finding thermography is essential. It is a non-contact, non-invasive diagnostic method.
Each of these procedures and methods has wide options of applications in medium voltage range and are important for maintenance personnel to understand. Metrel offers solutions that conform to international standards. Instruments provide elegant testing solutions with seamless connection to PC and automatic report generation.
Competencies at edison
EDISON is an international organisation for certification of competences in electrical safety testing. Click on the links for more information on each competency.
- EES: Earthing and grounding systems
- EEA: Electrical energy systems
- PQA: Power Quality Analyzing & Reporting
- EEE 81-2012 – IEEE Guide for measuring earth resistivity, ground impedance, and earth surface potentials of a grounding system
- EN 50522 – Earthing of power installations exceeding 1 kV a.c.
- IEC 62305 – Protection against lightning
- IEC / HD 60364-6 Low voltage electrical installation safety: Part 6 Verification
- EC / EN 60909 Short-circuit currents in three-phase a.c. systems
- IEC / EN 60947-2 Low-voltage switchgear and controlgear – Part 2: Circuit-breakers
- IEEE 519 Reporting and evaluating of the results
- EN 50160 Voltage quality reporting and evaluating of the results
- IEC 61000-4-30/-7/-15 – Power quality measurement methods, testing and measurment techniques