Protective Relay Testing for Safe Industrial and Commercial Operations
A relay may only need to operate for a fraction of a second in its decades-long life, but that moment can prevent extensive damage, prolonged outages, and worker injury. In a typical application, Protective Relay Testing should be conducted at least every two years in accordance with NFPA 70B.
Regular protective relay consulting, testing, and maintenance helps find and correct problems before they become expensive headaches. Quad Plus can test all protection elements, including metering (voltage and current) and functional testing. Upon evaluation, we can repair, retrofit, or replace your relays.
How Protective Relays Keep Your Electrical System Safe
The purpose of protective relays is to detect abnormal conditions or faults in an electrical system and then act to isolate or de-energize the affected part of the system. Protective relays prevent damage to equipment such as motors, generators, and transformers that can occur from short circuits, overloads, and faults.
Protective relays use a variety of sensing elements to measure and monitor the energy moving through a power system. By comparing measurements to programmed values, anomalies and abnormalities are detected, and the protective relay signals the circuit breaker to trip and isolates that segment of the system.
Common Problems Relay Testing Can Help You Catch Early
One of the most common reasons for protective relays to fail is contamination from an outside source. For example, cleaning agents or other materials used during machine operation can get inside a relay and cause problems. When metallic elements contaminate a relay, it can block the movement of the mechanical parts in the relay. Other types of contamination can create an open circuit.
Another common cause of failure is the degradation of the contacts in the relay and the physical wear of the contacts or other components over time. High voltage spikes, in-rush currents, and other conditions can cause a shortened working life of the contacts, and this deterioration can be further sped up if contamination is present.
What Exactly Is Protective Relay Testing, and Why Do You Need It?
The only way to determine if a relay is working correctly is to test it or wait for an equipment malfunction and hope it is operational. The problem with the second approach is the potential for catastrophic failure and worker injury.
Protective relay testing typically follows one of three methods. Acceptance testing is for new equipment and should be completed after installation and before energizing. Periodic routine maintenance tests are performed at regular intervals to test for the deterioration of electrical components over time.
Special maintenance testing is performed when equipment is known to be defective or has been exposed to adverse conditions, and functionality must be confirmed before the component can be energized again.
Which specific testing procedures a protective relay should undergo will depend on the age of the device, its condition, and the manufacturer’s recommendations.
Custom Relay Testing Solutions That Fit Your Needs
Comprehensive relay testing and maintenance procedures are different for each type of relay and are determined by the manufacturer’s recommendations and special application considerations. NETA-recommended protection relay testing procedures include:
- Inspection for mechanical problems.
- Pickup on each operating element.
- Timing at three points on the curve.
- Target and seal-in operation.
- Special tests for restraint, directional overcurrent, and other special operating elements.
- Insulation tests.
- Actual breaker trip test.
- Peripheral and auxiliary device tests.
- Function test.
Here’s How Protective Relay Testing Works
When a sudden power surge hits your electrical lines, relays signal the switchgear to trip off. Protective relays are the most potent defense against extended, costly outages and extensive equipment damage.
The tests we perform include:
- 1
Full Voltage Simulation. We run a power-simulating device programmed to the specifications of your equipment. This pushes secondary voltage into the relay to simulate primary voltage into the relay.
- 2
Full Current Simulation. We run a power-simulating device programmed to the specifications of your equipment. This pushes the secondary current into the relay to simulate the primary current into the relay.
- 3
Test All Protection Elements. We run the power simulator, which simulates faults in the relay. We can verify that the equipment is tripping within the manufacturer’s predetermined tolerances.
- 4
Functional Check of Main Device. We run the power simulator into the protective relay at proper trip settings. This will verify that the relay will trip off the switchgear it protects when we simulate a fault.
Making Sure Your Relays Meet Industry Standards
When relays are tested, technicians ensure that the relays are calibrated correctly to operate within standard parameters under fault conditions. The Institute of Electrical and Electronics Engineers (IEEE) and the International Electrotechnical Commission (IEC) provide a series of standards covering relay testing.
Standards are included for performance criteria, testing plans, and testing techniques, including which protective relay test equipment to use. Performance standards can include tripping and reset times, time delay, pickup level, and accuracy.
Testing plan standards outline which tests to perform, the conditions to put relays under, and expected outcomes. Standards for testing techniques include different types of testing equipment and data recording methods.
To ensure that your relays meet all industry standards, reporting guidelines include documenting all test results and performance characteristics, as well as listing any deviations from expected outcomes and behavior.
Protect Your Equipment with Protective Relay Consulting and Testing
Defective relays can cause minor issues, such as sudden equipment tripping, but they can also lead to disastrous consequences for your equipment and workers.
Routine testing and maintenance identify malfunctioning relays before they cause expensive, dangerous problems. Acceptance and commissioning tests will ensure that new equipment is assembled and installed correctly and ready to be energized for the first time.
Partner with the industry’s most experienced technicians to create a maintenance schedule that will save you time, money, and costly downtime.
Frequently Asked Questions
According to ANSI/NFPA 70B, relays in industrial settings should be tested every two years. IEC and other standards dictate a maximum of three years between tests. In most cases, the age and state of the relay, along with the manufacturer’s recommendations, will be used to determine if more frequent testing is required.
According to ANSI/NFPA 70B, relays in industrial settings should be tested every two years. IEC and other standards dictate a maximum of three years between tests. In most cases, the age and state of the relay, along with the manufacturer’s recommendations, will be used to determine if more frequent testing is required.
IEC 60255 is the current standard that provides requirements for measuring and testing relays and other equipment that protects electrical transmission and distribution systems.
