Static Control

1. Ministry of Technical Education and Vocational
Training (Yemen)
One Target Institute
Relay Logic Control
Classic Control
Eng.Waleed A.S Al-Akwa’a Sep 2019-22

2. Introduction to classic control
*The first invented relay.
• Joseph Henry 1835
The improvement of the industry and
manufacturing obligated to look for
new technologies like classic control.

3. Introduction to classic control
• Components of system that
mounted in a panel which is
called control panel
1-Circuit Breaker
2-Contactor
3-Overload
4-Switches
5-Connection Points
6-Timers
7-Cables
8-Ducts
9-Counters

4. Introduction to classic control
Relay is: A switch whose operation is activated
by an electromagnet is called a "relay“.
contact
coil
input

5. Introduction to classic control
• Circuit Breaker
• Contactor
*Electric device that protect
circuits from increased current.
*Works as a relay but with high
rates of current.

6. Introduction to classic control
• Overload
It is a tool was designed to protect loads(motors) in case of increasing the electric
current over the rated current.

7. Introduction to classic control
• Switches
• Indicator Lamps
• Connection points

8. Introduction to classic control
• Timers
A timer consists of an internal clock, a count value register, and an
accumulator. It is used for or some timing purpose.
Clock
Accumulator
contact
reset
output
Register
Contact

9. Digital counters output in the form of a relay contact when
a preassigned count value is reached.
• Counter
Register
Accumulator
contact
input
reset
output
Introduction to classic control

10. • Cables
• Ducts
Introduction to classic control

11. • Loads
IEC 60947 Standards
Introduction to classic control

12. Loads, Circuit Breakers and
Cables

13. After this section, you should be able to:
• Estimate the induction motors loads and compute the overall panel
power.
• Select proper circuit breaker(CB) for each load and panel.
• Select proper cable.
• Read and understand the name-plates.

14. Induction motors loads have important parameters must be
known:
• Power factor.
• Voltage.
• Rated current.
• Nominal current.
• RPM Speed.
*How can we calculate the rated current?
-Actually there are three ways to do that:
1-Electric power law. [P=V*Ir*p.f].
2-General Equation.([Ir=S*1.5], S=P/p.f).
3-Standarized schedules.

15. Loads differs in three aspects:
1-Selection of suitable conductor.
2-Selection of suitable circuit breaker.
3-Selection of other panel components.
Here are some standards of load types:
IEC 60947 Standards

16. Standardized schedules:
Ex/ If we have p=4kw and voltage with 390 V ?
-from the schedule, we see that rated current is 9.7 A.

17. • computing the overall panel power
-We will not go through that deeply, but if you want, you should read about electrical distribution.
*Here is an example to calculate the overall panel power.
If we have 3 motors, one is in use, other two motors are not and one is standby for the other.
First motor is 37 kw ,second is 30 kw and the third one is 30 kw.
*Note: we neglected one of the motors, due to work with only one motor.

19. • Circuit Breaker
Electric device that protect circuits from increased current.
-Types of Circuit Breaker in terms of structure:
1-One pole CB.
2-Three Pole CB.
-Types of Circuit Breaker in terms of characteristics:
1-MCB (Miniature CB).
-Fixed default value.
-Type of low voltage and current(100A-15KA).
-Certain value.
2-MCCB (Molded Case CB).
-Larger and higher short circuit capacity than MCB(3200A-100KA).
-Can be adjusted.
-used for main circuits and panels.
*three poles *two poles
MCB Types
MCCB Type

20. • Circuit Breaker
*How can we select the circuit breaker?
-Selection of circuit breaker depends on:
1-Calculation of rated current.
2-Calculation of short circuit current.
*What Next !!!!
-After we know the value of the short circuit current after the breaker, then we multiply it
by 1.25 which is a safety factor.
-Then we choose the nearest value of the standard values.
-We also choose the nearest value of the rated current from the standard values.
Ex
Short Circuit current(Isc): (5, 10, 15, 20, 25, 30, ………..130)KA standard values.
Rated current(I rated): (1, 2, 6, 16, 40, 50, 80, 120, 160, ……3200)A standard values.
short circuit current after the breaker:10KA
the value of the current:81.6A
Ans:
10KA*1.25=12.5KA =15KA
Rated current from the standards will be 80A.

21. Rated maximum current:
-Rated maximum current which can flow through the breaker continuously without any damage.
-The rated current of the line or system (on which breaker is installed) must be equal or less than the rated
current of the breaker.
Rated Short circuit breaking current:
-It is the maximum current which the breaker can break without any damage
• Circuit Breaker

22. • Cables
*Selection of the cable depend on the circuit breaker? Why!!?
-To make the breaker protect the cable not the opposite, that means if I have a 60A circuit breaker
and a 40A cable.
-After that if the current increased to 56A in the case of the overload’s absence, the cable will not be
able to carry that for long period so the cable will be cut.
-But if I brought a 80A cable, when the current increased to any value bigger than 60A and smaller
than 80A, the circuit breaker will break the circuit and the cable will stay operating.

23. Contactor

24. A magnetic contactor is an electrically controlled switch
used for switching a power circuit. It has main contacts
used for power circuit and auxiliary contact used for
control circuit.
main contacts
Auxiliary
contact(s)
Supply
terminals
Definition

25. HOLDING COIL
STATIONARY
CONTACTS
STATIONARY
CONTACTS
MOVABLE
CONTACTS AND
ARMATURE
COIL
CONNECTIONS
Structure

26. The principle of operation is similar to that of the relay
but differs in application.
State-off State-on

27. Way of connection

28. • Method of contactor selection:
-you have to focus on such things when you want to select a contactor:
a-Current and power of the load.
b-Number of the contact points.
c-Voltage of the control circuit.
*usually contacts are available with(9,12,16,20,25,…etc)A.
-Using catalogs:
Computational method
P=VI (watt)
Catalogs methods

29. Testing
-How to test the contactor:
1-By using Avometer(switch it to the alarm).
2-By using Omhometer(show 1 when on ,show 0 when off).
3-You must test it before you begin using it.

30. Damages
What should be done when any component of the contactor was damaged
1-If the coil was burnt out , windings must be rolled up again.
2-If the contact points were corroded, they must be changed.
3-If there was a layer of carbon on the contact points, they must be polished.

31. THERMAL OVERLOAD RELAY

33. • Agenda
 Definition.
 Structure.
 Idea of operation.
 Way of connection.
 Selection.
 Testing.

34. Thermal overload relay is an electrical component used
in motor control applications which provide protection
for motor against excessive current.
Definition

35. Structure
Line
terminals
reset
Set value dial
Auxiliary contact(s)

36. Principles of operation:
This component has a bimetal
strip that is made of two
dissimilar metals bonded
together. The two metals have
different thermal expansion
characteristics, so the bimetal
strip bends at a given rate
when heated.
As current rises, heat also rises. The hotter the
bimetal strip becomes, the more it bends. In
an overload condition, the heat generated
from the heater will cause the bimetal strip to
bend until the mechanism is tripped, stopping
the motor.
36

37. Way Of Connection:
Typical set-up of contactor and overload relay
37

38. Characteristics:
1. Allow harmless temporary overloads (such as motor
starting) without disrupting the circuit.
2. Trip and open a circuit if current is high enough to cause
motor damage over a period of time.
3. Can be reset once the overload is removed.
38

39. • Methods of overload selection:
-Using catalogs:
Catalogs methods
 Important note :set the overload current to the actual pulled value of the load not to full load
current.

40. Testing
-How to test the overload:
1-By using Avometer(switch it to the alarm).
2-You must test it before you begin using it.

41. Timers

42. • Agenda
 Definition.
 Structure.
 Idea of operation.
 Way of connection.
 Selection.
 Testing.

44. TIMER
A timer consists of an internal clock, a count value register,
and an accumulator. It is used for some timing purposes.
Clock
Accumulator
contact
reset
output
Register
Contact
Time 5 seconds.
Clock
Reset
Output
Count 1 2 3 40 5
Definition

45. Structure

46.  ON Delay
 OFF Delay
Main types of timers

47. Way Of Connection:

48. • Methods of timer selection:

50. Testing
-How to test timers:
1-By using Avometer(switch it to the alarm).
2-You must test it before you begin using it.

51. Counter

52. COUNTER
Digital counters output in the form of a relay contact when a
pre-assigned count value is reached.
Register
Accumulator
contact
input
reset
output
Input
Reset
Output
Count 0 1 2 3 4 5 0 1
5

56. Thank u
^_^
You can find me at:
waleed0alakwaa@gmail.com
Phone774275408