Protection Relay Testing Service Company in Dubai - UAE

Carelabs is authorized provider of Electrical Installation’s Study, Analysis, Inspection, and Certification services in UAE, and offer protection relay testing service.

What is Protection Relay and Why Testing is Important

Protection relays are switches that open and close circuits electro-mechanically or electronically. Thus controlling one electrical circuit by opening and closing contacts in another circuit. Factors like Contaminated atmosphere, operating voltage, overload, insulation aging etc. affect the performance of relays.

Like the saying prevention is better than cure, the timely protection relay testing will reveal catastrophic failures which would have prevented the relay from performing when called upon to operate, and properly maintained records will reveal any trends which could lead to such failures. Periodic Maintenance Checks are required to identify equipment failures and degradation in service, so that corrective action can be taken. Because a protection scheme only operates under fault conditions, defects may not be revealed for a significant period of time, until a fault occurs. Regular testing assists in detecting faults that would otherwise remain undetected until a fault occurs.

How Protection Relay Testing is Done?

A good set of testing equipment and relay tools are used by our inspectors. Several manufacturers now produce portable relay test sets that will provided excellent results.

Following are the various steps that we perform for protection relay testing:

Visual Inspection Of Protection Relay Testing:

Before the relay cover is removed, a visual check of the cover can reveal valuable information as well as prevent possible trouble. First, of course, excessive dust, dirt or metallic material deposited on the cover should be noted and removed. Removing such material will prevent it from entering the relay when the cover is removed. The presence of such deposits may call attention to the need for some form of air filtering at the station. Included in this visual inspection should be a check for loose connections, broken studs, burned insulation, and dirty contacts. Each relay should be checked to be in agreement with its setting sheet.

Mechanical Inspection Of Protection Relay Testing:

All connections should be tight. If several connections are found loose, excessive vibration may be indicated and should be corrected. All gaps should be free of foreign material, and should excessive foreign material be found, inspection of the gasket is in order. Moving gaps (contact gaps, armature gaps, etc.) should be measured and the values compared with previous measurements. Should there be a large variation in these measurements, excessive wear may be indicated, in which case the worn parts should be replaced.

Electrical Type Protection Relay Testing:Functional Tests

The functional tests consist of applying the appropriate inputs to the relay under test and measuring the performance to determine if it meets the specification. They are usually carried out under controlled environmental conditions.

Rating Tests Rating type tests are conducted to ensure that components are used within their specified ratings and that there are no fire or electric shock hazards under normal load or fault condition of the power system. This is in addition to checking that the product complies with its technical specification. The following are amongst the rating type tests conducted.

Thermal Withstand The thermal withstand of VT’s, CT’s and output contact circuits is determined to ensure compliance with the specified continuous and short-term overload conditions. In addition to functional verification, the pass criterion is that there is no detrimental effect on the relay assembly.

Electromagnetic Compatibility Protection Relay Testing:

There are numerous tests that are specified to check the working of protection relays and ability to withstand in various working environments. EMC tests determine the impact on the relay under test of high-frequency electrical disturbances of various kinds.

D.C Interrupt Test This is a test to determine the maximum length of time that the relay can withstand an interruption in th auxiliary supply without de-energising, e.g. switching off, and that when this time is exceeded and it does transiently switch off, that no maloperation occurs.

A.C. Ripple on D.C. Supply This test (IEC 60255-11) determines that the relay is able to operate correctly with a superimposed a.c. voltage on the d.c. supply.

D.C. Ramp Down/Ramp Up This test simulates a failed station battery charger, which would result in the auxiliary voltage to the relay slowly ramping down. The ramp up part simulates the battery being recharged after discharging. The relay must power up cleanly when the voltage is applied and not maloperate

High Frequency Disturbance Test The High Frequency Disturbance Te.