The consequences of loadshedding on municipalities’ primary plants and substations have been widely reported. Nishan Baijnath, Systems Architect, Power Systems, Digital Automation at Schneider Electric says the reality is, municipalities are in survival mode. He says they need realistic solutions to, by and large, protect equipment and prevent unplanned outages.
In his view, with municipalities’ distribution centres and equipment severely strained due to loadshedding, maintenance has moved down the priority list. Baijnath suggests that now is the time to implement measures to safeguard what municipalities can control – protecting and monitoring installed equipment.
Protection relays play a fundamental role in the protection of people, machines and equipment. For example, a protection relay can prevent hazards such as arc flash, which has the potential to cause devastating damage to substations as well as serious injury or fatalities.
Ideally a protection relay should be easy to install, require very little power to run, protect LV and MV distribution systems and control live distribution from a safe distance.
Why protection relays
Protection relays are, in essence, smart devices that receive information input, compare it to set points, and provide output. Inputs include current, voltage, resistance, or temperature and outputs incorporate visual feedback in the form of indicator lights and/or alphanumeric display, communications, control warnings, alarms, and turning the power off and on.
A protection relay can detect abnormal conditions in the electrical system and automatically operate the circuit breaker to isolate this condition.
Importantly, once a protection relay detects a fault, it will automatically operate the breaker’s trip circuit. The faulty circuit will be disconnected from the system and the circuit breaker will be open.
Considering the above, there are several important features that municipalities and industrial facilities should look for when installing protection relays. Schneider Electric recommends the following factors should be considered.
- Ease of use – a protection relay should save time and money with simplified configuration and operating processes. The Schneider Electric Easergy P1 protection relay can be configured with an HMI (human machine interface) and mounted in a matter of seconds with spring clips. It provides for easy operation with a built-in, dedicated circuit breaker control.
- Versatility – a protection relay should be optimised for MV protection on overcurrent, voltage and frequency, and serve as the main protection on LV applications when ANSI functions are required. Support for serial communications should allow for integration with control systems, to provide operators with accurate information at critical times.
- Flexibility – it should be optimised for compact switchgear and offer graded functionality tailored to specific applications. The design should allow for new and retrofit installations. The Easergy P1 can be used in a feeder, motor, or generator applications.
- Enhanced safety and reliability – it should have an insulated casing and non-volatile memory for settings and records as well as clock retention (for at least three days) and minimal power consumption.
Schneider Electric’s P1 protection relay features a plastic casing which prevents corrosion resulting from humidity and chemicals. Furthermore, the P1 is tiny, just 106 mm x 106 mm, which means it takes up very little space yet plays a critical role in keeping facilities safe.
Protection relays should form part of any electrical system, providing operational stability and importantly, safety.
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