The Basics of Single Phase Motors

Posted by IER Services on Sep 22, 2018 1:43:45 PM

Single Phase Power System

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Topics: single phase motors, split phase motor, shaded pole motor

Electrical Motor Winding Analysis

Posted by IER Services on Aug 1, 2018 4:17:10 PM

IER Services can help you detect and resolve motor issues using our state-of-the-art electrical motor winding analysis.   

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Topics: electric motors, electric motor winding analysis

Detecting Cracked Rotor Bars

Posted by IER Services on Jul 26, 2018 7:04:00 AM

Do you suspect that you have a cracked rotor bar in your electric motor?  Broken rotor bars rarely cause immediate failures, especially in large multi-pole (slow-speed) motors. Broken rotor bars precipitate deterioration in other components as well and can result in time-consuming repairs and loss of motor efficiency. 

Here are some methods to help detect cracked or broken rotor bars:

GROWLER TEST - A growler is an electrical device used for testing insulation of a motor for shorted coils. A growler consists of a coil of wire wrapped around an iron core and connected to a source of alternating current. When placed on the armature or stator core of a motor the growler acts as the primary of a transformer and the armature coils act as the secondary. A "feeler", a thin strip of steel such as a hacksaw blade or metal filings can be used as the short detector. For best results the rotor should be heated.

SINGLE PHASE ROTOR TEST - Single phase power is applied to the motor while the rotor is slowly rotated.  Using an analog meter, any fluctuation in amp draw is monitored. Lower or increased stator current is a sign that one or more cracked rotor bars are present. This test is best performed with the rotor heated and while the motor is still intact.

HIGH CURRENT ROTOR TEST - This test is performed by applying high current through the shaft of the rotor thermally scanning the rotor searching for shorted laminations. (Laminations are the steel portions of the stator and rotor consisting of thin lamination sheets stacked together.)

Hot spots can be caused by shorted laminations. This can result in uneven heating of the rotor which then causes the rotor to bow and go out of balance. Stress to the bars and premature bar cracking and fatigue are most often the result. A loose rotor to shaft interference fit can also be detected with this test.

INDUCTION MOTOR CURRENT ANALYSIS (CURRENT SPECTRUM TEST) - This test is considered the most accurate and reliable. It is performed while the motor is under 50 - 100% load. The rotor induces currents back in the stator windings.

These appear as side bands around the supply line frequency (60 HZ) peak, and are a function of the motors number of poles and slip frequency (the difference between synchronous speed and operating speed, at the same frequency, expressed in rpm, or in percentage or ratio of synchronous speed.) An estimate of the number of broken rotor bars can be determined by comparing the sideband amplitudes.


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Topics: cracked rotors, electric motor repair

Bell & Gossett 's Parallel Sensorless Controller

Posted by IER Services on Jun 8, 2018 9:00:08 AM

Xylem Inc.’s Bell & Gossett  brand has a new  parallel sensorless controller, a device that provides advanced system staging of up to eight pumps in parallel configuration to maximize system efficiency.  The large 5.7-inch touch screen displays real-time feedback and enables energy modeling.

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Topics: Bell & Gossett, sensorless controller

Jet Pump Basics

Posted by IER Services on May 30, 2018 3:03:19 PM

Jet pumps are used for a variety of applications involving the movement of water from a water source to a destination. If your home is supplied primarily by well water, you may need a jet pump to pull the water. 

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Topics: jet pumps, centrifugal pump, shallow well pumps

7 Ways Gauges Can Extend Pump life

Posted by IER Services on May 23, 2018 8:03:00 AM

Pressure gauges and switches are among the most often used instruments in a plant. Monitoring your gauges and regular maintenance can help you avoid expensive and unexpected shutdowns.

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Topics: pumps, pressure gauges, pump gauges, isolation valves, transducers

Electric Motor Shafts

Posted by IER Services on May 11, 2018 8:02:00 AM

The key component in most rotating equipment is the shaft. A shaft is the mechanical component for transmitting torque and rotation. Shaft size greatly affects the torque in these machines. Hence, the precise design and prototyping of shafts is crucial for all applications.  

Choosing the proper material can maximize reliability. When considering the best material for your electric motor shaft, there are several considerations: Cost and Material Deficiencies.   

The material used for ordinary shafts is mild steel, but when high strength is required, an alloy steel such as nickel, nickel-chromium or chromium-vanadium steel is used.

Most motor manufacturers use SAE 1045 in either cold-rolled (CRS) or hot-rolled steel (HRS). C1045 is a medium carbon, medium tensile steel supplied as forged or normalized. This steel shows good strength, toughness and wear resistance. 

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Topics: shafts, electric motors

Armstrong End Suction Pumps Add Unique Vibration Isolation Technology

Posted by IER Services on May 4, 2018 1:00:00 PM

Armstrong Fluid Technology has announced the availability of a new line of high performance Design Envelope End-Suction pumps in the 1 to 10 hp range.

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Topics: Armstrong pump repair

Now is the Time to Install a Backup Generator

Posted by IER Services on May 4, 2018 12:47:11 PM

When you’re at home and the power goes out you can light candles, but if you have a power failure at your business you need a better solution.  You may want to invest in an emergency-power backup.      

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Topics: backup generators

Commercial buildings need a systems approach to maximize efficiency

Posted by IER Services on Mar 20, 2018 3:46:57 PM

Commercial building managers are challenged to improve the energy and water efficiency of their buildings. This is driven by new building codes that continue to raise efficiency standards for new and existing buildings, pressure to cut energy costs wherever possible and corporate sustainability initiatives. Facility managers of existing properties are increasingly adopting a systems approach to energy and water efficiency improvements. 

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