Industrial Electricity: Installation [2]

3 Phase Induction Motor controller

 This is second part of installation but I try to write first because any training program that must be held before the time. In this part of discussion we will trying more deeply about induction motors, any components that commonly used in it, and induction controller of 3 phases motors.  

 A. Induction Motors

As we know in a motors the main part can be divide into two parts. They are rotor (part of moving) and stator (fix part). In this time commonly used motor are one and three-phase motor. First we will talking about one phase induction motor.

       A.1 One phase motor

       Pic1 one phase motor

          This kind of motor is commonly used in household equipment such as mixer, blender, juser,etc. This is sample equipment that used one phase motor:

Pic2 Some equipment use in one phase motor

One phase motor have already same construction with three-phase. In this kind of motor we need any starter to make a rotor turn around. Starter of this motor can be divide into two-part they are electric starter and mechanical starter.

Pic3 One phase motor with resistor starter

                In one phase motor consist of primary and secondary convolution. Above picture can draw that current will flow to Im (primary convolution) and be a reason of the rotor to turn around CW (clock wise), this because in secondary convolution resistance more higher. On a pic3 asked that is an electrical starter. We can use mechanical starter when we use centrifugal force to pointed the direction of motor turn around.

        A.2 Three phase motor

Pic3.Three phase motor

Three phase motor have construction as we seen at pic3 above. This type of motor haven’t special starter as one phase has. This type of motor work him self and to conducting their direction it depend of the pole. We can make an equation about velocity of the motor they have by:


Ns = Velocity in RPM

f = frequency in Hertz

n = the number of poles  ex, commonly in two, four and six (coil)

Equation above draw that velocity depend of the number of poles and frequency. The difference of motor direction depend of the installation of phase R ,S, T. If we need to make an other direction we must change over a pair of phase. This is the philosophy of motor direction:

Piic4. Three phase R,S, T

Three phase R, S, T is not mean they are work together in a time but they will work one by one in a time. We can see there are the common poll that is used:


Pic5 Motor two poles

Pic6 Motor four poles

Pic7 Motor six poles


B. Electric Component

       B.1 Contactor (C)

      This picture below drawn contactor that commonly used in industrial electricity:

    Pic8. Contactor

         From picture we can see that contactor have two main parts they are coil and contacts. Coil A1 must get fuse and A2 must get Neutral as a requirement to make contactor active.

          In a contactor there are two kinds of contact they are main and assist contact. Main contact consist of three NO (normally open) that will conduct power way. We called them L – line (Consist of L1, L2, and L3 all of this line connect with three-phase R, S, and T)  and T line (consist of T1, T2, and T3 all of this line will connect into motor U, V, and W cables).

         In an assist contact there are NO (normally open, remain by number 13-14 or 43-44), and NC (normally closed, remain by 21-22 or 31-32). We can used this assist contact in control way.

        B.2 Timer (T)

         This picture below drawn timer delay that commonly used in this object:


           In the picture above we can understand that timer have two coil (2 n 7) that must be connected with phase and neutral as a requirement.  Timmer have a pair of NO (1-3 or 8-6) and a pair of NC (1-4 or 8-5). The function of timer is to delay a time. So they have a number of mode. They are delay on, delay off or sequences.

           Timer have four kind of mode operation they are, A, B2, E and J.

 A mode is called as “on-delay” that mean will be on if the time is reach what be sett.

B2 is called as “flip-flop delay” this mean time of on-off will change depend of the time sett on the timer.

E is called as “off delay” that mean off will reach when the time reach on.

The last is J mode that called as ” a sequence delay” that mean the condition of the time will change into first condition depend of the sett of the time.

Hopefully this picture will explain you about my explanation:

 Pic10. Mode of timer

          B.3 Thermal Overload Relay (TOR)

 The picture below drawn the TOR schematic:


           We can use this component to cover overload because of over the current or an other reason. TOR have two contact there are main and assist. as contactor the function of main contact is used in power way and assist contact just have by control way.


 C. Three phase induction motor controller

 In the installation, we can divide into two-way of installation there are:

– Control installation (220v, a phase)  and

– power installation (380v, 3 phase)

In this case I will figure it out by this picture below:

Pic12. Control and Power installation

We will divide the installation of three phase motor into several part they are:

a.  Control the movement of motor with contactor (by button and switch) switch button

b. Control the movement of motor with timer and TOR

Pic15.Load contro by TOR

c. Control the movement of motor from two different place

Pic16.Two difference place controller

d. Control the movement of motor and the direction

Pic17.Movement two motors

Pic18. Control direction of motor by 3 button

Pic19. Control with a limit switch

Pic20. Control with two limit switch

e. Control of breaking the movement motor with diode

Notice : “this is the end of trainee…hopefully add a new value for us”


“Danke Schoen”

Auf Wiedersehen

Date : 14-16 November 2011

Placed : Jakarta, Polman Astra on SRI training

Written : Lin Prasetyani (adapted from Mr.Afianto, Internet and related book of electricity)

Download pdf in Indonesian version here:


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