Category Archive for: «Motor»

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8 NEC Basic Feeder Circuit Sizing Requirements

Feeder circuit loads Once the branch circuit loads are calculated, the feeder circuit loads may be calculated by applying demand factors to the branch circuit loads. General Lighting Loads (Article 220.42) Show window or track lighting (Article 220.43) Receptacles in other than dwelling units (Article 220.44) Motors (Article 220.50) Fixed Electric Space Heating (Article 220.51) […]

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PLC Implementation Of Forward/Reverse Motor Circuit With Interlocking

Forward/Reverse Motor Interlocking Figure 1 illustrates a hardwired forward/reverse motor circuit with electrical and push button interlockings. Figure 2 shows the simplified wiring diagram for this motor. The PLC implementation of this circuit should include the use of the overload contacts to monitor the occurrence of an overload condition. The auxiliary starter contacts (M1 and […]

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Characteristics And Work Principles of Switched Reluctance (SR) Motor

SR Motor Characteristics The Switched Reluctance (SR) motor is very different from the other polyphase machines described because both the stator and the rotor have salient poles. The motor can only be used in conjunction with its specific power converter and control, and consequently only overall characteristics are relevant. The intuitively straight forward principle of […]

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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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