Improving Electrical Reliability by Implementing Motor Circuit Analysis
When you want to determine the health of your motor, Motor Circuit Analysis (MCA™) is a preferred choice in any industry. This deenergized motor testing method allows you to gauge the entire health of your motor, transformer, generator, and other coil-based equipment in just a few minutes. MCA’s thoroughness helps you determine a motor system’s electrical health and increase your equipment’s electrical reliability.
What Is MCA?
Motor Circuit Analysis is an impedance based measurement technology that injects a Non-destructive low voltage AC sinusoidal signal through the motor winding system that exercises the entire motor insulation system to identify any unbalances in the windings that would indicate either a current or potential motor fault. In a perfectly healthy electric motor all three phases will be identical to each other meaning all measurements acquired will also be identical. A deviation of measurements between phases signifies a developing or current fault.
MCA allows the user to quickly analyze and identify the following motor faults:
- Ground Faults – Measure the resistance between motor’s winding system and the motor frame (ground) to determine if the motor is safe to run. This value is typically measured in Megaohms (Mohms).
- Rotor Faults – Rotor faults are determined my measuring the impedance values of all three windings as the rotor rotates in the magnetic field of the stator. Typical rotor faults are broken or fractured rotor bars and casting voids that develop during rotor manufacturing. These faults are typically not seen by eye so they will go unseen until catastrophic failure occurs unless proper testing strategies are utilized.
- Internal Winding Shorts – Motor Circuit Analysis is capable of determining early stage turn to turn, coil to coil, and phase to phase internal winding shorts. Being able to determine these faults is what separates Motor Circuit Analysis from conventional motor testing practices. These faults develop as slight changes to the chemical makeup of the winding insulation material which means standard resistance readings will not detect these changes until a direct short between two conductors is made and a catastrophic failure occurs.
You can initiate MCA directly from the motor or at the Motor Control Center (MCC). By testing from the MCC, you can evaluate the entire motor system such as the motor starter or drive, motor cables and connections between the motor and test point. This testing method stands out from the competition, as no other motor testing technology has these capabilities and because MCA injects a low voltage signal into the motor circuit there is no need to disconnect a Variable Frequency Drive (VFD). MCA’s in-depth testing helps you easily spot errors and quickly take action to increase electrical reliability.
How Does MCA Work and Increase Electrical Reliability?
Test Value Static
One of the main elements of MCA solutions is the Test Value Static (TVS), which helps you maintain electrical reliability in your motor. A motor’s TVS is essential, as it lives with the motor from the cradle to the grave and can help you spot issues that could cause poor electrical reliability. MCA calculates a motor’s TVS by taking measurements on all three phases of a motor. After taking these measurements, they’re put through a proprietary algorithm that produces a single number.
Reference Value Static
When a baseline test is taken on a new or recently repaired motor, the TVS value is referred to as the Reference Value Static (RVS). This value lives with the motor until it fails and is commonly referred to in future tests. With MCA, you can then compare the baseline RVS and a new TVS. If these values show a deviation of over 3%, a fault is likely developing, meaning you should troubleshoot further.
By quickly calculating RVS and TVS and comparing the results, MCA systems help you increase electrical reliability. When your readings show higher-than-acceptable deviations, you can make repairs before the motor’s electrical reliability is severely impacted.
Another way MCA equipment helps improve electrical reliability is through its incorporation of software. MCA software allows you to create a route that guides you to the most critical motors at your facility to prevent unnecessary downtime and save money.
MCA can detect developing turn to turn, coil to coil and phase to phase faults before any other motor testing technology. By detecting these faults, the software allows you to make a maintenance and repair plan to protect your motor’s electrical reliability and prevent failure.
Motor testing software also allows users to efficiently organize test records and trend results over time. With historical records, you can more easily determine when equipment’s health is decreasing and has the potential to fail — ensuring your motors deliver consistent electrical performance.
MCA Testing Applications
MCA testing has many applications designed to check your motor’s electrical health and ensure everything is working appropriately. Find out more about the primary MCA testing applications below:
- Incoming inspection: Even new motors can fail, and MCA ensures a new piece of equipment is in working order before you start using it. With MCA, you can perform an incoming inspection to evaluate the health of a new or recently rebuilt piece of equipment. This testing eliminates the chance of installing a defective motor that won’t operate correctly once installed.
- Commissioning: Before installing a motor from the stock shelf, you can use MCA for commissioning, where you conduct a motor test to establish a baseline test result. This result gives you a value to reference in the future to determine a change in the motor system. Once the motor is installed in the machine, you can take another baseline test directly from the MCC. You then have two baseline tests to compare to future tests to evaluate the overall condition of the motor system
- Troubleshooting: If a motor develops issues like intermittently tripping a motor drive, drawing too much current, or overheating; a Motor Circuit Analysis test should be performed directly at the MCC. If a fault is identified, then a second test should be conducted directly at the motor. If the fault remains, the fault can be isolated to the motor and appropriate action can be made to replace the motor or send it to a rebuild facility to have it repaired. If the fault clears at the motor, then there is most likely an issue from the MCC to the motor cables. At this point, the motor cables should be analyzed as well as any connections made at a local disconnect or magnetic contactor. Corrosion due to moisture and high humidity can create high resistant connection points or even loose connections creating an impedance or resistance imbalance which will eventually lead to excessive heat and or imbalanced current draw of the motor. Without corrective action, this will greatly reduce the life of the motors and motor cables in the system and possibly cause safety implications.
- Preventive and predictive maintenance: Minimize downtime and plan for potential motor failures by implementing a predictive maintenance program on your most critical machines. With MCA software, you can save money and prevent downtime by creating a route that guides you to your most essential motors. Specific measurements can also be trended to help identify developing motor faults before they become a concern. By trending test results with the Motor Circuit analysis software a technician can create easy-to-read reports and once the results hit predetermined criteria the technician can create a plan to have that motor replaced before it fails to ensure the least amount of downtime as possible. With MCA’s ability to find faults faster than any other motor testing technology, you can easily catch issues early and perform preventive maintenance.
Choose ALL-TEST Pro for Your MCA Equipment Needs
At ALL-TEST Pro, our motor current signature analysis equipment is among the best on the market today. We have a variety of motor testing software equipment and hand-held MCA equipment available, such as the ALL-TEST PRO 7™ PROFESSIONAL, ALL-TEST PRO 34 EV™, MOTOR GENIE® Tester and ALL-TEST PRO 34™. Our broad selection ensures you can find a perfect fit for your equipment and testing requirements. By using our equipment, you can maximize your motors’ efficiency and productivity and give your maintenance team the tools they need to stay on top of your motors’ health.