MEG-alert Motor Guard helps prevent motor failures.
How? In two very important ways:
First, Motor Guard gives you an accurate test of the insulation resistance within the motor. Insulation resistance (as measured in meg-ohms) is the measure of the quality of the winding insulation. This measurement of insulation quality essentially tells you how much electrical current is "leaking" from the motor to the grounding connection.
In a new motor this resistance is high - as high as 100 meg-ohms. The resistance declines over time as the motor is subjected to heat, vibration, power spikes, and other usage factors including exposure of the insulation to chemicals. Resistance is also lowered by external factors, primarily moisture, dirt, and other contaminants. When the insulation resistance is low, electrical current can "leak" to the ground instead of being contained within the insulated motor windings, which results in a "burned out" motor.
When a motor burns out (assuming it is not mechanically damaged) the only remedy is "rewinding" the motor. Unfortunately, this is an expensive procedure costing upwards of 50% or more of the cost of a new motor, plus labor costs to remove and reinstall the motor. While rewinding does have some savings over replacement, it is a one-time fix as few motors can ever be rewound a second time. In addition, a rewound motor is typically less efficient than a new motor - producing less horsepower and drawing more current.
On the other hand, motors that are worn (but not burned out) can be reconditioned for about 10% to 25% of replacement. This involves reinsulating the undamaged windings. A reconditioned motor will return to like-new condition with no loss of efficiency.
The problem is: How do you know when a motor is ready for reconditioning?
The ONLY way is to test each critical motor. That is exactly what the MEG-alert Motor Guard does automatically and continuously.
The MEG-alert Motor Guard model pictured above includes a meg-ohm meter. This meter has an easy-to-read scale with an intuitive "green-yellow-red" dial. the green area represents a high level of insulation resistance. When the testing process is underway (ALL the time the motor is offline, 24/7) the Test On green light will flash and the dial will give the exact meg-ohm level.
The meg-ohm level can be recorded by any staff person - it does not require a trained electrician. The meg-ohm level can even be transmitted to a remote location. A terminal is provided on the Motor Guard for an optional relay.
When (not IF) the insulation resistance falls below 10 meg-ohms (that is, only 10% of the original condition of the new motor) the Motor Guard enters the "Pre-Alarm" stage, depicted by the yellow range on the meter. The motor will still start and run, but the insulation is weak and preventive maintenance should be scheduled.
The Pre-Alarm level is also indicated by a flashing yellow LED and can be further reported by accessory lights, alarms, or remote monitoring options. If the motor is installed in a series with backups, the backup motor should now be brought online to allow for repairs or reconditioning. These repairs could save the motor AND could save 75% to 90% of the cost of replacement.
Let's illustrate the difference in dollars:
- A medium voltage motor may cost in excess of $50,000.
- Rewinding this burned out motor would cost at least $25,000.
- Reconditioning this motor before it burnsout would likely cost $10,000 or less!
Which invoice would you rather pay?
Now you could perform a meg-ohm test of the motor manually. But most motors are not tested regularly because of the time, expense, and danger of conducting these tests. Electricians must have access to the motor when the plant is not in operation (inconvenient.) Electricians must access the high voltage motor controls (dangerous.) And, electricians must conduct these tests over and over again on every critical motor (tedious, repetitve, inefficient, and prone to human error.)
- Instead, MEG-alert Motor Guard is installed ONCE.
- Motor Guard is installed so the meg-ohm reading is clearly visible on the OUTSIDE of the motor control cabinet.
- Meg-ohm testing becomes a "hands off" process; completely safe.
- Motor Guard allows for recording trends in insulation resistance, which in turn allows for proactive "predictive" maintenance versus reactive emergency repairs.
- Meg-ohm testing becomes a continuous process providing accurate information at every instant the motor is offline - right up to the moment the motor is started.
This last benefit involves the SECOND main way that Motor Guard prevents motor failures.
Most motor failures occur as the motor is starting. Up to 95% of burnouts occur under the added stress of coming up to speed while the motor typically draws more current than under steady operation. For example, the "in rush" of current to a 480 volt motor can be as high as 2000 volts during startup! In contrast, as little as 325 volts will cause a failure if insulation resistance is too low. As a result of the added strain and added current, a motor that has low insulation resistance will burnout.
As described above, this low resistance could be caused by deterioration of the winding insulation gradually over time. Or the resistance could be artificially low because of the introduction of moisture, dirt, chemicals, or anything else that would act as a conductor of electricity within the motor. The resulting ground will cause a catastrophic failure of the motor.
But the MEG-alert Motor Guard clearly shows the meg-ohm reading on the external dial. When this level falls below two meg-ohms (that is, only 2% of the new motor) failure is not a possibility but an absolute certainty!
Note: MEG-alert can customize the alarm level. Typical applications use from one meg-ohm to as high as five meg-ohms.
At this very low level of insulation resistance, Motor Guard will also flash a red LED. Additional lights, alarms, or remote contacts can also be activated. But the most important safeguard provided by Motor Guard is a starter lockout feature.
When the MEG-alert Motor Guard measures dangerously low insulation resistance, it will inactivate the starter control of the motor. In other words, the motor can NOT be started - either locally by pressing the "Start" button or remotely if connected to an automatic circuit. The motor can not be started until the problem causing the alarm is corrected and the Motor Guard is reset.
If you don't know the condition of the motor (either mechanically or environmentally) and you attempt to start the motor when the insulation resistance is in the danger levels, the motor will fail. This is a mechanical certainty.
However, if the motor is protected by MEG-alert Motor Guard and the starter is engaged, the motor will not be allowed to start, and is prevented from burning out.
Again, it does not matter WHAT has caused the low resistance. The Motor Guard will provide a meg-ohm test of the motor continuously up to the moment before the attempted start. If the resistance is dangerously low, the lockout will prevent the motor from starting - and save ther motor.
Note: manual meg-ohm testing is also a valid option. However, in order to provide the same protection the manual test MUST be performed at the moment IMMEDIATELY preceding motor startup. Because environmental conditions often factor into motor failure, it is USELESS to rely on manual tests performed days, weeks, or months ago! Obviously, for a motor that is cycled on and off, it is impractical to schedule an electrician to perform repeated tests on a daily basis.
MEG-alert Motor Guard both eliminates manual testing AND improves the quality of the testing exponentially.
MEG-alert Motor Guard provides unmatched benefits in combination with patented features.
Want more information? Check out the FREE information at:
www.prevent-motor-failures.com
MEG-alert Motor Guard helps prevent motor failures - TWO ways!
Without Motor Guard you can only assume the condition of critical motors.
Use Motor Guard in your preventive and predictive maintenance program to both minimize repairs expenses and maximize plant efficiency!
Call TODAY for a NO Obligation, FREE consultation.
MEG-alert Corporation 866-768-1817
info@meg-alert.com