Category Archive for: «Motor»

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Comparision of Direct-on-line (DOL) and Star-delta Motor Starting

Motor starting methods // Direct-on-line (DOL) starting Advantages Drawbacks Star-delta starting Advantages Drawbacks Comparision of DOL and Star-delta starting Direct-on-line starting (DOL) As the name suggests, direct-on-line starting means that the motor is started by connecting it directly to the supply at rated voltage. Direct-on-line starting, (DOL), is suitable for stable supplies and mechanically stiff […]

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Calculation of motor starting time as first approximation

Motor starting operations The problems connected to motor starting operations are fundamentally linked to the type of motor which a determined motor operational torque “CM” offers, to the starting modality and to the connected load which has a determined load torque “C ”. A generic curve of the above mentioned quantities is shown in the Figure […]

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Basics of DC Motors For Electrical Engineers – Beginners

General about DC motors Separate field excitation DC motors are still sometimes used for driving machines at variable speed. These motors are very easy to miniaturize, and essential for very low powers and low voltages. They are also particularly suitable, up to high power levels (several megawatts), for speed variation with simple, uncomplicated electronic technologies […]

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5 Most Common Motor Load Types

Load profile (speed range, torque and power) Certain load types are characteristic in the industrial world. Knowing the load profile (speed range, torque and power) is essential when selecting a suitable motor and frequency converter for the application. Some common load types are shown. There may also be combinations of these types. Constant Torque Quadratic […]

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Basics of Built-in Motor Protection for Beginners

Why is motor protection necessary? In order to avoid unexpected breakdowns, costly repairs and subsequent losses due to motor downtime, it is important that the motor is fitted with some sort of protective device. This article will deal with built-in motor protection with thermal overload protection to avoid damage and breakdown of motor. The built-in […]

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Motor Connection for Clockwise and Counterclockwise Direction of Rotation

Star-delta (Y-Δ, wye-delta) starting Star-delta (in North America the designation “wye-delta” is commonly used instead) starting is the simplest method for reducing the starting current of a motor. The technique can be used with all squirrel-cage induction motors that are delta-connected for normal operation and whose windings ends are individually connected to terminals. The reduction […]

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What To Check When Commissioning Variable Speed Drives

The purpose of commissioning VSDs The main purpose of commissioning VSDs is to ensure that: The AC converter and motor have been correctly installed and meet the wiring and safety standards such as IEC 60364 or Australian standard AS 3000. The power and motor cables are correctly sized, installed and terminated. All power cable shields […]

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Comparison of Motor Speed Control Methods

Why motor speed control? It is often desirable to control the motor speed, usually for reasons process control for such variables as flow or pressure. Such applications as fans and pumps often have varying output requirements, and control of the motor speed is more efficient than mechanically limiting the process output with such devices as […]

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The Most Common LV/MV Motor Starting Devices

Two-state ON-OFF device The most common motor starting device is the low voltage motor-starting contactor. A contactor is defined as “a two-state ON-OFF device for repeatedly establishing and interrupting an electric power circuit.” Contactors are designed for optimum performance and lifetime when switching loads; they are not designed for interrupting short-circuit currents and therefore motor circuits require separate […]

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4 Types of DC Motors and Their Characteristics

Characteristics As you already know, there are two electrical elements of a DC motor, the field windings and the armature.The armature windings are made up of current carrying conductors that terminate at a commutator. DC voltage is applied to the armature windings through carbon brushes which ride on the commutator. In small DC motors, permanent […]

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