b'30 Partner News Spring 2021EnterpriseSynchronousdisplayed, altered, stored, and printed. If settings are stored in a setpoint file, they can be downloaded instantly to the relay via a computer cable connected to a personal computer. Another advantage Motor Protectionis that each settings file can be archived, such that if the installed relay fails, a replacement relay can be quickly commissioned with equivalent settings.Panel RetrofitThe process of transferring existing protection settings from old electromechanical relays to numerical relays requires extra diligence. A single mismatch can potentially cause severe Guidelines:problems to the power system equipment. A typical, electromechanical relay will have less than 10 settings that are set with plugs and switches. Thus, in the A Case Study case where electromechanical relays are used, it is more practical to store the settings by hand on relay settings sheets. Mistakes are often made either in tabulating the relay settings or in managing changes in settings. Care has to be taken to ensure that the information provided on the relay setting sheets corresponds to the relay commissioning tests results By Yurinov Mambauas well as relay manual guidelines before relay programming can be done. The (Graduate Electrical Engineer, EES) total absence of these relevant records during a retrofitting project is a major challenge for design engineers.Once relay settings information has been confirmed, the next step is the programming of the numerical relay. In the case where a protection study cannot be done, efforts are made to duplicate existing settings as closely as possible. The Currently, there are a number of existingsystem are reliability and flexibility.exact duplication of relay settings is not legacy power stations and industrialReliability is the simplest issue to address.always possible, due to the many different plants across the world which requireJust replacing the original relays withmethods of providing fault detection. protection retrofits. These retrofitsmore modern, compact versions can include the transfer of existing protectionincrease the lifetime of control panels.For instance, the out of step protection settings from an array of stand-aloneelement operates differently across the electromechanical relays to a single multi- With respect to flexibility, numericalrange of popular numerical relays. functional numerical relay. Consideringrelays allow for alterations in protectionSome electromechanical relays measure that, electromechanical relays are limited infunctions without changing wiring.the change in power factor when the motor both intelligence and size, numerical relaysThis can be done simply by enabling orloses synchronism by comparing the phase are widely embraced due to their advanceddisabling certain protection features withinA line current with the voltage across digital communication capabilitiesthe relay. Besides, protection settingsphase A and B. Conversely, a method and fault disturbance recording. Thiscan be reprogrammed at any time.more suited to the greater mathematical potentially eradicates trouble shooting capabilities of a numerical relay measures problems in a complex relay scheme. To simplify programming, numericalthe positive sequence apparent impedance protection relay setpoints can be enteredand traces its locus with respect to the Apart from diagnostics, the two largestwith a PC running the associated software.position of the blinders and the mho drawbacks to a traditional relay logicActual values and setpoints can becharacteristics.'