ELECTRICAL CONTROL
PANNEL
Electrical Control Panel
An electrical control panel is a metal box which contains important electrical devices that control and monitor a
mechanical process electrically.
Enclosure:
*The enclosure, the metal electrical control box that contains all of the electrical devices of the control panel. Enclosures are often
aluminum or stainless steel and the size will vary based on the size of the process.
*An electrical control panel enclosure can have multiple sections. Each section will have an access door.
*The size of the enclosure is commonly referred to by the number of doors the enclosure has.
*Each enclosure will have an electrical safety rating designated by UL, the “Underwriters Laboratories” who governs electrical safety.
*They will also have an IP rating or NEMA classification which designates the enclosure to be indoor or outdoor, waterproof or water-
resistant, suitable for hazardous conditions, dustproof, or explosion proof.
Back Panel, DIN Rails, Wiring Ducts:
**The back panel is a sheet of metal that is mounted on the inside of the enclosure that allows us to drill mounting holes for different
devices which leads us to our next component, DIN rails.
**A DIN rail is a metal rail with a standard width used for mounting electrical devices inside.
**The next component inside the electrical control panel is wiring Duct.
**Ducts allow us to route the wires in an organized and efficient way while also reducing electrical noise between devices.
Electrical Components of a Control Panel:
1)Main Circuit Breaker:
The main circuit breaker is where the power comes into the control panel for all of the devices. This circuit breaker generally
has a disconnect on the outside of the panel that allows us to shut off the power.
Always remember the topside of the circuit breaker will still have power. The power that comes into the panel can be
anywhere from 480 volts to as low as 120 volts.
2)Surge Arrester
After the power comes into the panel from the main circuit breaker the power will be run into a surge arrester. Surge
arrester is a device that protects all of the electrical equipment inside the control panel from electrical surges or
overvoltage. An electrical surge can come from a lightning strike or utility power surge.
3. Transformer and 24-Volt Power Supply
The power can be connected into a transformer that switches the power
down in order to power smaller devices.
If the incoming power is above 120 volts, a transformer is generally used.
If the power is 120 volts, a power supply can be used to step the power down
to 24 volts.
4. Terminal Block:
A terminal block consists of two terminals that can join two or more wires
together.Terminal blocks can be arranged with several other blocks in a strip
mounted on a DIN rail to run power from one source to several devices
throughout the panel
5. Programmable Logic Controller (PLC)
Next part of the control panel is a device that controls and
monitors the mechanical process.
Let’s talk about the PLC or Programmable Logic Controller.
The PLC is like the brain of the entire process.
The PLC will have a CPU where the logic program is stored.
It will have associated inputs and outputs which will help control and monitor the Assembly line.
Speaking of our terminal blocks, we will have wires running from them to our inputs and outputs.
This allows for the actual control of the assembly line.
Field devices such as proximity switches, photo eyes, and other sensors are set up on the assembly
line to give the feedback needed for the PLC to control the operation of the line.
6. Relays and Contactors:
The PLC outputs will be wired to a bank of relays that will
close an internal contact that will send power out to turn ON
or OFF a device on the assembly line.Smaller relays will
control devices such as lights or fans while a bigger relay,
called a “contactor”, is used to control motors.
7. Network Switch
We will also have a network switch located somewhere
near the PLC.
This will be powered with 24 volts and it will be the HUB
for our communication to and from the PLC to network
compatible devices on the assembly line.
8. Human Machine Interface (HMI)
One of those devices is our “Human Machine Interface” or
HMI. An HMI can be mounted locally onto a panel door or
in a remote panel located closer to the machinery.
The HMI can be a very dynamic tool in assisting the
operator in controlling and monitoring the machinery.
The PLC will pass signals over the network to the HMI for
monitoring and the HMI can send signals to the PLC for
controlling the machinery.
Why to use a Protection Current Transformer with an Electrical Panel?
The Protection Current Transformer is used to provide the currents to protection Relay.
These current transformers have their primary winding connected in series with the
conductor which carries the current to be measured or controlled.
Rated primary current – Defined by standards. Such as 10 – 12.5 – 15 – 20 – 25 –
30 – 40 – 50 – 60 – 75 A and their decimal multiples.
Rated secondary current – either 1A or 5 A.
TRANSFORMER/FEEDER PANEL:
33KV & 11 KV Transformer Control circuit in the Panel is required for control Or Protection on 33 &
11 KV side of 33/11 KV respectively.
The various components of these panels are described down here as follows:
Single Point Annunciator (SPA).
Circuit Healthy-1(TCH-1) LED (white)
Trip Circuit Healthy-2(TCH-2) LED (white)
Breaker OFF LED (Green)
Breaker ON LED (Red)
Fault/Auto Trip LED (Red)
D.C. Fail LED (Red)
Buchholz Trip LED (Red) for 33KV transformer
Buchholz Alarm LED (Amber) for 33KV transformer
Winding Temperature Trip LED (Red) for 33KV transfor
Continued---
**Winding Temperature Alarm LED (Amber) for 33KV transformer
**Oil Temperature High Trip LED (Red) for 33KV transformer
**Oil Temperature High Alarm LED (Amber) for 33KV transformer
**Oil Low Level Alarm LED (Amber) for 33KV transformer3 Alarm Accept Push Button
** PB-4 Alarm Reset Push Button
** PB-5 DC Fail Test Push Button
Different types of panels:
** MCC Panel : Motor contro Centre
** PCC Panel : Power control Center
** APFC Panel : Automatic
powerfactor Control
** LT Panel
** AUTOMATION Panel
** INTELLIGENT MCC Panel
Relays used in contro panel::
*Buchholz relay
*Over Current relay
*Master trip relay
*Earth fault relay
*Auxiliary relay
Advantages
**Availability of Stats and logs
**DNS management
*”Easy Management
**Easy Installation
Disadvantages
**Fixing permission issues
**Difficulty in big tasks
**Server Security
Thank you
