Standard Terminal Markings of DC (Direct Current) Motors

Standard terminal markings, as developed by NEMA, are given for series, shunt and compound motors in figure 1, figure 2 and figure 3 respectively. These figures all show compensating-field as well as commutating-field windings since they are intended to cover both fractional horsepower and integral horsepower motors. Fractional horsepower motors do not generally use compensating windings and they may not use commutating-field (interpole) windings.

The markings are combinations of letters and arabic numerals, generally, these are as follows:

- Armature - A1, A2
- Control signal lead - C
- Series field - S1, S2
- Shunt field - F1, F2

Reversing DC Motors

Procedure for reversing direct current motors

Direct current motors are reversed by changing the direction of current flow through the armature or through the field. In series motors, the usual procedure is to reverse the current through the armature. Figure 1 shows this method.

All that is necessary is to interchange the leads on the brush holders. Figure 2 shows the series motor reversed by changing the current in the field circuits.

Commutating Field (Interpole) of DC Motors

Nearly all shunt and compound motors of 1/2 horsepower or more have commutating fields or interpoles located between the main poles. These interpoles have one winding of heavy wire and are connected in series with the armature as shown in figure 1. The purpose of the interpole is to prevent sparking.

Types of Direct Current (DC) Compound Motors

Figure 1: Two-pole compound DC motor

The motor shown in figure 1 above is one of the four different types of compound wound DC (direct current) motors. Although this type is known as the most common form of connection, it is the one used most often and the one which should be used unless otherwise specified. It is essential also to discuss the other types of compound wound DC motors.

Wiring Connection of Direct Current (DC) Motor

Connecting Direct Current (DC) Motors

It is of utmost importance to firstly know and understand the various internal configuration of the different types of DC motors before doing the actual wiring connection.  Although DC motors may appear to only have two leads for its external wiring connection terminals, it will serve best to habitually apply a good practice of knowing first the type of DC motor you are about to install before attempting any wiring connection and supplying power to run the motor.

Types of Direct Current (DC) Motors

Fundamental types of Direct Current (DC) motors:

1.) Series Field DC Motor - The series field DC motor contains field coils composed of a few turns of wire connected in series with the armature as shown in Figure 1 below.  This motor has high starting torque and a variable speed characteristic.  The greater the load the motor carries, the lower the speed.

Fundamental Overview of a DC Motor

Direct Current Motors - DC Motors are used to convert DC energy into mechanical energy. They are well suited for use as either constant-speed or adjustable speed motors. The three types (Shunt, Series, and Compound) which are available provide the range of speed torque characteristics for applications which require:

Warbling Alarm Circuit

The Warbling Alarm is made up of sawtooth wave generator and voltage controlled tone generator operated in tandem. Q1, R1, R2, C1, R3 comprise the sawtooth wave generator.

At the instant power is applied to the circuit, the voltage across C1 and hence at the anode of Q1 would be zero. C1 would then be slowly charged by R3 towards +12V. Once the voltage across C1 exceeds the value of the voltage appearing on the gate of Q1 as set by R1 and R2, the PUT (Programmable Unijunction Transistor) fires, that is, it will conduct, causing C1 to quickly discharge.Once C1 is discharged, Q1 will turn OFF, causing another charge - discharge cycle to be initiated. The manner in which the voltage across C1 varies, when plotted against time, resembles a sawtooth, hence the name sawtooth wave.

Inserting Alarm System to an Oil Pump Control Circuit

At some point in time, you may happen to have an old industrial pump unit wired inside an existing control panel that would require circuit modification in order to include an alarm system. What is being referred to here are pump systems most commonly found in industrial facilities such as oil pump, hydraulic pump, grease pump, water pump, air pump or air compressors, but nevertheless, the electrical circuit presented in this article may also be used to set an example to provide idea for other similar applications.

In heavy industrial facilities, one of the important foundation of a good working machinery is dependent on the condition of a well-oiled mechanism. This pertains to having a reliable lubrication system that ensures all moving parts of every machinery in the factory are well-lubricated in order to diminish friction and grinding on the machine's mechanical joints and contacts.

Electrical Circuit for Controlling a Lifting Electromagnet for Overhead Cranes with Top Running Trolley Hoist

When the need to conveniently pick up and lift heavy iron or steel objects for transferring from one place to another was seen as a necessity in heavy industrial facilities, the concept of using an electromagnet was implemented due to its ability to be turned ON and OFF which was then incorporated effectively to the hoist function of overhead cranes.

Overhead-travelling-crane magnets are electromagnetic device attached to the crane's hook to magnetically pick up heavy metallic loads for hoisting and transferring.  Cranes that are fitted with a lifting magnet are equipped with an electromagnet control circuit.

Wiring Connection for a Three Wire Solid State DC Proximity Sensor Without PLC

The previous article illustrated the concept of the wiring connection of a 3 wire DC proximity sensor to a PLC (Programmable Logic Controller). Alternatively, in this article, I will explain another approach on the wiring connection of the same proximity sensor but without using a PLC.

How to Connect a 3 Wire DC Solid State Proximity Sensor to a PLC

Knowing how to connect a 3 wire DC solid state proximity sensor to a PLC (Programmable Logic Controller) is dependent on the type of proximity sensor and the PLC to be used that is specific to the design of the circuit and the preferred application.

Pinch Roller Automatic Grip Control After Shear Cut Using PLC Program

What is a pinch roller? A pinch roller is a rotating machine consisting mainly of two rollers arranged in parallel either horizontally or vertically depending on the process required to pull the material that is rolled in the mill. These two rollers are coupled to a variable speed electric motor which is constantly rotating at a preset speed that is synchronized with the speed of the preceding finishing roller located before the pinch roller.

Electrical Wiring Diagram Forward Reverse Motor Control and Power Circuit Using Mitsubishi PLC

This blog post is not only intended to provide a graphical illustration but will also explain the procedure and the operational concept involving the wiring principle of the forward reverse motor control circuit with the use of a PLC (Programmable Logic Controller).

A diagram of the ladder program contained inside the PLC memory specifically for this function is also included below to clearly illustrate the operational sequence for command execution of this motor control system.

Electrical Wiring Diagram Star Delta Control and Power Circuit Using Mitsubishi PLC Program

This article is intended to diagrammatically demonstrate the concept of the wiring principle of a star delta (wye delta) motor control and power circuit when using a PLC (Programmable Logic Controller) ladder program to control the switching of a 440 volts induction motor.

Motor Start Stop Time Sequence Electrical Control Circuit Using PLC Ladder Program

The following is a sample tutorial of a typical timing sequence involving a start and stop function of a common DOL (Direct On Line) motor control circuit using PLC (Programmable Logic Controller) ladder program.

Types of electrical circuit connections - Basic tutorial on series and parallel circuit

There are mainly two basic types of circuit connection in an electrical system. These two basic configuration are most commonly known as the series connection and the parallel connection.

Although there are a lot of other complex circuits constructed from various designs and installation purposes to suit specific electrical requirements, all of them are based from a combination of these two basic wiring principle.

Learn how to use an electrical multimeter - A basic introduction tutorial and multimeter manual

Introduction:

When you get behind the wheel of a car, what is the next thing that you would most certainly do besides closing the door and strapping yourself securely to the seat. Obviously enough, it is expected that you would turn the ignition to start the engine, grab the steering wheel, shift the gear and step on the pedal because this is the most basic routine that every driver would instinctively do to drive a car. This inherent trait almost comes as a second nature to all experienced driver, which simply is an automatic pattern of behavior in reaction to the specific situation of driving a motor vehicle.

Similarly, having an aptitude for using an electrical multimeter would always come in handy when working with electrical circuits. Just as it is vitally important to have a thorough understanding about what makes up the structure of an electrical circuit, which involves the installed electrical switching components that are connected in such a way as to provide a continuous controlled flow of electrical path between the circuit's supply or source voltage down to the connected load in the circuit, so too is the importance of using a multimeter in circuit analysis.

Why it is Important to Learn How to use an Analogue or Analog Multimeter / Multitester

While digital multimeters are extensively used nowadays as it is the most common electrical test meter preferrably chosen by every electrical technicians in every electrical industry, considering its widespread popularity for ease of use and with its abundant availability of choices in a wide variety of functions and features in almost every brands and models out in the market these days, yet still there are times when you are caught in certain situations when you are left with no choice but to use the traditional analog multimeter when a digital one is not on hand, where you would most probably find yourself so helpless, unable to do anything but to just hopelessly stare at the darn thing with frustration, not knowing where to begin and how to use it since you are more accustomed to modern multimeters which are all digital instruments.