What is Electrical Control Panel?

Electrical control panels are designed and used to control mechanical equipment. Each one is designed for a specific equipment arrangement and includes devices that allow an operator to control specified equipment.

Electrical panel components control every piece of equipment in every industry. It’s difficult to describe all possible combinations because every industry and most companies have defined component preferences.

If you need to come up to speed on control panels fast, take your time. Find someone to help you, someone who knows what you’re trying to do. Start with the basics and build from there. Below are the basics.

Electrical Control Panel Descriptions

If control panels are new to you and you want to learn about them, the first step is learning the terms used to describe them. What are the major descriptive categories and how is each one described? Below is an example of how to describe important control panel attributes.

1. Safety Ratings

   • 3rd Party Safety Certification = UL508A (cULus)
   • Short Circuit Current Rating (SCCR) = 5kA

2. Enclosure Ratings

   • NEMA Rating: NEMA 4X Outdoor
   • Material: 304 Stainless Steel
   • Mounting: Wall Mount
   • Door Mechanism: Lockable Handle with 3 Point Door Latch

3. Main Power

   • Incoming Power: 480V 3 Phase through a Main Circuit Breaker
   • Outgoing 480V Power:
     • 480V 5.0 HP Fan through a Motor Starter
     • 480V 1.0 HP Pump through a Motor Starter

4. Control Power

   • 120V and 24VDC
   • 480V-120V Transformer
   • 120V-24VDC Power Supply
   • Outgoing 120V Power: Chemical Pump through a Power Relay

5. Door Mounted Operator Devices

   • Main Circuit Breaker Operator
   • Fan:
     • Hand-Off-Auto Selector
     • Fan Running Light
     • Low Flow Light
   • Recirculation Pump:
     • Hand-Off-Auto Selector
     • Pump Running Light
     • Low Flow Light
   • Sump pH Meter (Signet)
   • Chemical Pump:
     • Hand-Off-Auto Selector
     • Running Light
     • Tank Low Level Light

6. Sequence of Operation

   • Supply Fan:
     • In Hand: Run Supply Fan
     • In Auto: Monitor Air Flow Switch to verify Air Flow above minimum Flow Rate. Alarm and stop Supply Fan if Air Flow below desired Flow for X Seconds.
   • Recirculation Pump:
     • In Hand: Run Recirculation Pump
     • In Auto: Monitor Water Flow Switch to verify Water Flow above specified Rate. Alarm and stop Recirculation Pump if Water Flow below minimum Rate for X Seconds.
   • Chemical Pump:
     • In Hand: Run Chemical Pump
     • In Auto: Monitor Chemical Tank Level Switch to verify Chemical Level above minimum Tank Level. Alarm and stop Chemical Pump if Chemical Level below minimum Tank Level for X Seconds.

7. Remote Control Interface

   • Digital (Dry Contact) Inputs:
     • System Enable Contact
   • Digital (Dry Contact) Outputs:
     • System Local-Off-Remote Selector in Remote Contact
     • Fan Running Contact
     • Pump Running Contact
     • Chemical Tank Low Contact
   • Analog (4–20mA) Outputs:
     • pH signal from Door Mounted pH Meter (Signet)

A control panel consists of a controller. The controller may be PLC, DCS, relay, or some other type. It gives a digital signal input to the MCC panel to start the motor. The control panel works based on the PLC/DCS program or the relay logic. Instruments are normally connected to the control panel. Indications for the interlocks will also be there in the control panel. Nowadays, a single panel is used instead of separate control and MCC panels.

Ease in modification of logic, reduced size, means of remote communications, and advances in technology have made PLC Automation Control Panels an edge over conventional relay-based systems. Control Systems Engineers have provided PLC-based Panels from Allen Bradley, Siemens, Modicon, and GE Fanuc. From small I/O applications to the complex I/O systems, Control Systems Engineers provide solutions. They have also developed communication software for remote communication of the PLC Panels in various different protocols. With PLC-based Panels, HMI/MMI are provided to give the operator various messages and control of the process plants via touch screen MMI.