Solutions for Substation Maintenance
The need of keeping the reliability of power systems requires suitable substation maintenance. A failure of only one substation equipment can cause a grid collapse, which may cost a large time and money to solve, so that the substation maintenance programs limit the risk of unexpected outages by identifying and preventing potential problems.
Typical inspection and diagnosis processes of the substation maintenance plans include transformers, breakers, switchgear, panels, motors & generators, ground grid and protective relays, among others; their reliability can be established by equipment testing under simulated operating conditions; each one of the devices will require different attention in the substation maintenance strategies, but all of them must be supported by state of the industry test tools.
Typical testing in substation maintenance and related SMC test equipment
One of the critical pieces in substation maintenance is the circuit breaker. Typical checked parameters are the open and close timing operation, poles synchronism, contact resistance, coils condition, DC batteries status and motion analysis. The small and friendly SMC PME-500-TR includes all mentioned functions that can be required in the substation maintenance plans for MV/HV circuit breakers, and reduces the testing time, combining two sets in one.
Our new PRIME micro-ommeter is also best suited for circuit breaker testing in substation maintenance, the only micro-ommeter that combines both static and dynamic resistance measurement (DRM), with smart and wireless control up to 600 A of true pure DC. The PRIME is a universal micro-ohmmeter for testing the integrity of any connection during the substation maintenance.
The trip tests, both thermal and shorcircuit trips, of low voltage circuit breakers and molded-case circuit breakers, are better performed with the flexible and powerful Raptor System, with the smallest size and weight of the market.
It is also essential in the substation maintenance the verification of the entire protection scheme to verify live CB tripping, in combination with total trip time including the IEDs. The combination of mobility, adaptability, automatic output regulation, high-tech, ease of use and versatility makes the Raptor the best system available for all primary injection testing applications in substation maintenance.
The substation maintenance includes periodic electrical testing of different parameters of the transformer, being common the checking of some key magnitudes such as turns ratio, excitation current, polarization index, insulation resistance, winding resistance, short circuit impedance, etc. Those same electrical tests are the basis of the ETP system, the integrated SMC predictive power transformer maintenance system, composed by four modules which can also be used separately.
The multifunctional Raptor System also provides some power transformer test templates, such as withstand voltage, PT ratio, shortcircuit impedance tests and power factor.
Our PME-20-PH, digital phase angle meter, is other must-have tool for substation maintenance that provides phase deviation on power and metering transformers.
Current and Voltage Transformers
There are some common routine practices when testing protection and/or metering CTs/VTs, that usually covers transformer ratio, burden, polarity, phase deviation, excitation and insulation tests, among others. In this sense, the Raptor integrates the transformer testing of all kinds of CTs and VTs, with the high current and high voltage capability for the main primary injection applications in substation maintenance.
Motors & Generators
For the substation maintenance related to electrical motors and generators, the insulation resistance test system EDA-III evaluates the stator winding insulation to identify the main problems. Some of the parameters analyzed are insulation resistance, polarization index, leakage current ratio, capacitance ratio and reabsorption current.
The particular case of ground testing in substation maintenance includes many types of tests and related equipment depending on the objective sought; regarding the condition of the whole ground grid for the safety performance of the grounding system in the substation, the following solutions are included in the Raptor System:
- Ground Grid: Raptor template for detecting bad or eroded contacts in the ground grid, through high current method.
- Step & Touch Test: automatic function for measuring the step & touch voltage characteristics of the protective earthing installations in substations, and discovering ground potential rise hazards.
The switchgear panels integrate the control, measurement equipment and protection relays, busbars, current and voltage transformers, and the corresponding circuit breaker; the substation maintenance programs must ensure the proper working of all the components and their joint operation. For the transformers, busbars and breakers, the same equipment recommended in the relevant sections are also applicable here (RAPTOR, PRIME, PME-500-TR), with the addition of the SMC wide range of single and 3-phase secondary injection solutions to cover the diversity of applications in switchgear testing during the substation maintenance (MENTOR 12, PTE-100-C, PTE-50-CET, etc).
The panel testing during substation maintenance goes through many quality, inspection and test procedures regarding the electrical operation, which usually cover wiring and polarity continuity, dielectric resistance, functional testing of the protective scheme, relay testing, breakers testing, and other operational checks.
Single phase test sets are a must-have tool for simple and quick checking in substation maintenance (PTE-100-C series, PTE-50-CE PTE-100-V), while the complete verification of the tripping scheme, may require the use of secondary injection test sets with at least 3-phase functionality (PTE-50-CET, PTE-300-V, TRES) and more complex programmable testing functions (MENTOR 12).
Other applicable products for panels in substation maintenance are the Raptor System, the Raptor Polarity Tester, the Raptor HV, the digital phase angle meter PME-20-PH, the PME-10/100 and PRIME micro-ohmmeters, the digital timer PTE-30-CH, the IEC 61850 multimeter GOOSEmeter One, etc.
Many types of protection relays are found in the substation, with different protection functions, with different technology, in different positions, etc…The substation maintenance program may include from the couple of points test in a single-phase overcurrent relay to the most complex end-to-end schemes. So that, in the selection of relay testing sets for substation maintenance we must consider the adaptability of the equipment to different situations and requirements – and even to the skills of the staff. Our experience during the past 30 years has enabled us to have a complete range of equipment with different philosophies (PTE-100-C series, PTE range, MENTOR 12 platform, ROOTS automation software) for the various applications and situations, from the simplest and autonomous sets to fully automated, for quickly performing any type of relay testing in substation maintenance.
For more information, please check the related SMC products or contact us.