What is a Contactor & How it works & How to test [#2 Relay Logic Control]

a contactor is one of the basics of Relay logic Control(Classic control) & PLC ,this explanatory tutorial about what is it & how it works & how to test your contactor before the installation or during a maintenance or troubleshooting
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LinkedIn: / muhammed-hesham-
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I'm Mohamed an automation engineer with 5 years of experience in Electrical engineering .
I worked at different projects like CNC, ROV, Arm Robotics.
On my channel we 'll learn together about all industrial automation stuff like
Relay logic control (Classic control), PLC Programming, HMI,
Scada and electrical safety, and other stuff.
Hope we learn in an easy and funny way ✌🏼
Cheers

[@mahmudyoutube7145]

ممكن ارفاق نص الكلام باللغة الانكليزية والعربية على شكل نص
مثلا لتطوير اللغة الانكليزية للطلاب

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حضرتك تقصد احطهم مثلا ك كومنت ولا علي الفيديو ؟

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@@dotex2809 ممكن كومنت
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@@mahmudyoutube7145 ده الأسكربت وحضرتك تقدر كمان تشغل الترجمة من علي يوتيوب
To switch on this motor with this little switch we need a contactor, and by the end of this video we w’ll know what is a contactor , how it works and how to test your contactor before the installation or during a maintenance or troubleshooting
a contactor is an electromechanical switch
that works as the connection point between the control circuit and power circuit in a motor control system
a contactor establishes or interrupts high current delivered to a motor
but does that only at the request of a low voltage control signal
an operator can use a low voltage pilot device like a push-button
to turn on or off a high voltage load
so it’s offering a level of isolation and safety
A contactor paired with an overload element form the two necessary components for a motor starter
the contactor starts or stops the motor
and overload protects the motor from Continuous overload conditions
a contactor can be integrated with an overload in a single package called a motor starter
or the pair working together can be considered a motor starter
a contactor by itself can’t be considered a motor starter
since it can’t protect the motor from Continuous overload conditions
a contactor is consisting of a set of moving contacts
and it’s making-or-breakig a connection to a high-power electrical load like a three-phase AC industrial motor
these moving contacts are controlled by a low power control signal and it’s electrically
isolated and provided by the coil
additionally sometimes auxiliary contacts provide feedback about the state of a
particular contactor
this is an IEC schematic symbol for a contactor
these are the coil contacts
these are the auxiliary contacts
these are the normally open power contacts from l1 to t1
,these are the normally open power contacts from l2 to t2
And these are the normally open power contacts from l3 to t3
a contactor is named by the number of power contacts that does not include the coil or any connected auxiliary contacts
this is a three pole contactor that will be used to make or break a connection to an industrial motor
supplied by 480 volt 3-phase AC for example
the L side is sometimes known as the line side
the T side is sometimes known as the load side
when the low voltage control signal supplied to the coil ,the contacts would close
and the path from line to load will connect a huge power
a contactor for electrically controlled systems including motors
is similiar to the solenoid operated valve in an electrically controlled hydraulic system
the solenoid operated valve controls fluid power
but only at the order of the low voltage control signal
the low voltage control signal could be 24 volts DC 24 volts AC or 120 volts AC
this is the brain of the contactor
before we continue always read the manufacturer's datasheet for the specific contactor that you ‘ll use
do not for a moment assume the pin outs and specifications by yourself
the coil is part of another electromechanical device known as a solenoid
a solenoid means a device that takes one form of input and converts it into a mechanical movement
in this case the solenoid converts electrical energy of the control signal
into linear mechanical movement by an armature
sometimes called a plunger
when the coil is energized by a low voltage control signal
the armature is pulled into the coil
and the contacts attached to the moving plunger changed from the deactivated state to the activated opposite state
in this case , the three normally open power contacts would close
in other words the brain controls the muscles
the key point in the operation of a contactor
is keeping of electrical isolation between not only the coil signal and the high-powercontacts
but also between the three independent high power contacts
l1 to t1 is a normally open switch and it’s not electrically connected to the coil
the only link between the coil and any of the high power L to T contacts
is a non conducting physical one
therfore when the armature is pulled into the coil / these pairs close
additionally the L 1 to t1 pair is not electrically connected to the L 2 to t2 pair
or the L3 to t3 pair or any other combination
they are three independent normally open switches that when moved by the armature at the same time, they close or open together
so a contactor can energize or de energize a high-power electrical load when ordered to do
by the low voltage control signal
so the brain tells the muscles when to move
the auxiliary contact has the same control signal voltage
and it’s used to provide feedback about the particular contactor state
Auxiliary contacts of the contactor are used in control circuits and are not used in motor circuits
this particular contactor has one set of auxiliary contacts
since this is the first set of auxiliary contacts come with this contactor
the first digit would be one
since it is a normally open switch the second digit with these terminals ‘ll be three and four
so the terminals for this auxiliary contact is one three one four
contactors are often mounted in an electrical cabinet
hard wired connections to the terminals are sometimes hidden inside plastic channels
here is a three pole contactor
when it is in deactivated state ,the ohm meter indicates there is no connection between the L 1 and T 1 pair
nor the L 2 and T 2 pair
nor the L3 and T 3 pair
so there is no connection between any pair and any other pair
the three switches are open and electrically isolated from each other

the ohm meter indicates the coil between a1 and a2 has a resistance close to 370 ohms
and a damaged coil would show a different resistance
and If you see no measurement at all it’s an indication the coil wire is broken
this coil is designed to operate on either 110 volt 50 Hertz AC
or 120 volt 60 Hertz AC .
the ohm meter indicates no connection between the 1 3 and 1 4 terminals of the normally open auxilary contact as expected
both the coil and auxiliary contacts are designed to switch the low voltage control signals only
When the coil is deactivated or activated
The Power contacts T1 and T2 are not connected to each other and the ohm meter will show no connection
and when a coil is activated the power contact T1 and L1 are connected and the ohm meter would show no resistance
note that if a technician wishes to test the functionality of a contactor
before the installation or during a maintenance or troubleshooting procedure
access to the plunger of the contactor allows to turn on manually the contacts for inspection
purposes
when manually turned on , an ohm meter indicates there is a connection between the L 1 and T 1 terminal pairs
also L 2 to T 2 and L3 to T3
additionally the ohm meter indicates the normally open auxilary contact from 1/3 to 1/4 has closed
That’s it
Thank you for your valuable time
cheers

[@mahmudyoutube7145]

الله يجزيك الخير وينور عليك يا هندسة

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