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.