Category Archive for: «Motor»

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14 energy-efficiency improvement opportunities in pumping systems

Detailed energy assessment Pump systems consist of pumps, driver, pipe installation and controls (such as ASDs or throttles) and are a part of the overall motor system. Below some of the energy efficiency opportunities for the pumping system are presented. Also, American Society of Mechanical Engineers (ASME) has published a standard that covers the assessment […]

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Energy Efficiency Aspects of Electric Motors

Load Efficiency Three-phase squirrel-cage induction motors comprise a considerable percentage of the electrical load in the United States. Design, operation, and maintenance of these machines is well described in some of the articles already published. This technical article focuses on their energy efficiency aspects. Induction motors typically range in full load efficiency from about 87% […]

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8 Energy-Efficiency Improvement Opportunities In Electric Motors

Energy Saving Opportunities When considering energy-efficiency improvements to a facility’s motor systems, a systems approach incorporating pumps, compressors, and fans must be used in order to attain optimal savings and performance. In the following, considerations with respect to energy use and energy saving opportunities for a motor system are presented and in some cases illustrated […]

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13 features and advances of using electronic soft starters for a motor starting

Starting characteristic Soft starters serve for a continuous adjustment of the starting characteristic of three-phase asynchronous motors to the requirements of the load by controlling the voltage across the motor and enable for an optimum integration of the drives in process control by means of various complementary functions. While when star-delta starters are used, the […]

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A Few Words About Selecting AC Induction Motors for Cement Plant Applications

Introduction This technical article relies on the great paper written by Barton J. Sauer (Siemens Energy & Automation) which goes into essence of selecting the proper AC motor for cement plant applications. Although motors may appear to be the least complicated component in the specification of cement mill equipment, this article shall try to demonstrate that cement plant […]

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How to measure insulation resistance of a motor

Winding insulation resistance If the motor is not put into operation immediately upon arrival, it is important to protect it against external factors like moisture, high temperature and impurities in order to avoid damage to the insulation. Before the motor is put into operation after a long period of storage, you have to measure the […]

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PLC application for reduced voltage-start motor control

Reduced-voltage-start motor control circuit Figure 1 shown below illustrates the control circuit and wiring diagram of a 65% tapped, autotransformer, reduced-voltage-start motor control circuit. This reduced voltage start minimizes the inrush current at the start of the motor (locked rotor current) to 42% of that at full speed. In this example, the timer must be set to […]

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Motor Starting via Chokes or Resistors

Reducing the voltage and starting current The series-connected chokes (Figure 1) or resistors (Figure 2) reduce the voltage at the motor and hence also the starting current. The starting torque is reduced by around the square of the current. Starting via chokes At rest the motor impedance is small. Most of the supply voltage drops […]

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Physical Structure & Configuration of DC Machines

Two-pole machine Figure 1 depicts a two-pole machine in which the stator poles are constructed in such a way as to project closer to the rotor than to the stator structure. This type of construction is rather common, and poles constructed in this fashion are called salient poles. Note that the rotor could also be […]

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Inspection and test procedures for Rotating Machinery, Synchronous Motors and Generators

Procedures (Index) Visual and Mechanical Inspection Electrical Tests Test Values Visual and Mechanical Tests Electrical Tests Pictures: Electrical machine wired for electrical testing The Electrical Machines Laboratory TABLE 100.10 – Maximum Allowable Vibration Amplitude TABLE 100.12 – US Standard Fasteners 1. Visual and Mechanical Inspection Compare equipment nameplate datawith drawings and specifications. Inspect physical and […]

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