What are the Tests and Maintenances That Should Be Done on Separators?

Disconnectors are one of the most important equipment for maintenance safety in electrical facilities. Because the task of the separator is not only to open the circuit, but also to create a truly visible and reliable separation distance in the circuit. For this reason, the tests and maintenance that must be done on separators are not only to keep the equipment clean; It is done to ensure the safe work of personnel, to prevent wrong maneuvers and to guarantee the correct execution of the operating sequence. A working splitter may look solid from the outside; However, if there is wear on the contact surfaces, hardening of the mechanism, a gap in the interlock structure or an error in the position indicator, a serious safety risk may arise in the field.

The first step in separator maintenance is always safety. Before starting work on the equipment, the relevant line must be disabled with the breaker, the correct operating sequence must be applied, voltage-free voltage must be confirmed and, if necessary, grounding steps must be completed. When performing maintenance on the disconnector, not only the main power side, but also auxiliary feeds, control circuits and signal cables should be taken into consideration if there is a motor drive. Forgetting the control energy, especially in MV cubicles, may lead to undesirable movements during maintenance.

Visual inspection is the basis of separator maintenance. At this stage, dirt, corrosion, moisture, oil-dirt layer, cracks on the resin or porcelain surface, darkening in the terminal areas, traces of overheating on conductive surfaces, signs of leakage current in insulators and signs of partial discharge should be investigated. Color change, dulling or surface deterioration at the contact points often indicates an increase in contact resistance in the future. No matter how solid the separator appears, maintenance personnel should take these initial symptoms seriously.

The cleaning process is not an ordinary step, it is an application that directly affects the quality of care. Separator blades, fixed contact areas, insulator surfaces, drive connections and intra-cell insulating surfaces must be cleaned with an appropriate method. Dust combined with moisture can worsen leakage current behavior; Oily or sticky layers of dirt may make it difficult for the moving mechanism to operate properly. Wrong chemicals that will scratch the surfaces, damage the coating or leave residue should not be used during cleaning.

Checking electrical connections and mechanical connection points is another step that should not be neglected in disconnector maintenance. Busbar connections, cable connections, mechanical connection pins, joints, bolts and drive arms must be at the correct torque. Connections that become loose over time both increase the contact resistance and may prevent the separator from fully reaching the final position during operation. Especially in outdoor separators, temperature changes, vibration and environmental effects can accelerate these loosening.

Mechanical movement testing must be performed on separators. During the opening and closing process, it must be verified whether the blades are properly seated in the fixed contacts, whether the lever mechanism moves without getting stuck, whether the end positions are clearly reached and whether the position indicators are compatible with the actual physical situation. In three-position disconnectors, ON, OFF and EARTH transitions must occur in the correct order, without excessive force and in accordance with the operating logic. A mechanism that is left before reaching the final position can both damage the interlock structure and create a false perception of security.

Interlock systems are one of the most critical topics in disconnector maintenance. Because in many MV switchgears, the disconnector, breaker and earth separator are connected to each other with mechanical or keyed locking devices. The purpose of this arrangement is to prevent the disconnector from moving when the breaker is closed, the earth separator from closing at the wrong moment, or the maintenance access from being opened while a live section is present. These interlock systems should be tested one by one during maintenance; It must be checked whether the selector mechanism, lock tongues, key locks, padlock points and cover locks are working correctly.

In cells where a separator and an earth separator are used together, operating order verification must be made separately. Although sequences such as first opening the breaker, then switching the disconnector to the OFF position, and then moving the earth separator to the EARTH position, if necessary, are theoretically known in the field, they may actually become faulty due to mechanical misalignment or faulty installation. Therefore, it is not enough to just look at the opening and closing of the separator alone; The entire maneuver chain should be tried as a scenario.

One of the most valuable electrical tests that can be performed in disconnector maintenance is contact resistance measurement. Low resistance testing enables early detection of problems such as looseness, contamination, oxidation, contact surface degradation or loss of mechanical stress in the main conduction path. A significant difference between phases or an increase in resistance compared to previous measurements indicates that the separator should be examined in detail. Even if the contact resistance seems low, it is difficult to make a sound comment without following the trend; That's why record keeping is of great importance here.

Insulation tests are also an important part of separator maintenance. Measurements made in phase-soil and other appropriate insulation paths give an idea about contamination, moisture absorption, surface deterioration or insulation weakening. Insulation values ​​should be closely monitored, especially in disconnectors that are out of commission for a long time, in open field equipment or in systems operating under heavy pollution. A comparison with previous maintenance values ​​is also necessary as well as a one-time measurement; Because many problems do not occur suddenly, but with gradual deterioration.

In motorized separator applications, the drive mechanism and auxiliary circuits should be evaluated separately. It should be checked whether the motor carries the separator reliably to the final position, whether the limit switch structures work properly, whether the position feedback goes towards the SCADA or control system, and whether there is any delay or strain in the motor circuit. Many malfunctions seen in motorized disconnectors occur on the control and drive side rather than the main contact part.

Auxiliary contacts and position signals are also small but critically important elements. Even if the disconnector appears to be open, if the auxiliary contact sends incorrect information, incorrect status perception may occur on field displays or relay logic. Likewise, incorrect ground separator location information may mislead the maintenance team. Therefore, not only physical movement but also electrical feedback should be tested during maintenance.

At the end of the maintenance, all results must be recorded. Visual findings, tightened connections, cleaned areas, contact resistance measurements, insulation results, interlock tests, motor control tests and detected nonconformities should be monitored in a single maintenance file. In this way, not only the current situation but also the tendency to deteriorate can be seen during the next maintenance. In summary, the tests and maintenance that must be done on separators are; It consists of visual inspection, cleaning, connection tightness, mechanical movement verification, interlock and position indicator checks, contact resistance measurement, insulation tests and confirmation of the operating sequence with earth separator. If you want to use separators, soil separators and MV/HV cell equipment together in your facility HV/MV testing, maintenance and repairfor field design LV/MV/HV project design and consultancy and business processes SA operation responsibility It is possible to progress in integration with services.