A control panel serves as the point of control for controlling and monitoring the operation of a system, such as industrial equipment, manufacturing processes, HVAC (heating, ventilation, and air conditioning) systems, or even home automation systems. Control panel design refers to the process of creating the physical layout, electrical circuitry, and user interface for a control panel used in various systems and machinery. Some of the variables involved in a control panel design include:
- Sizing of the feeder A feeder circuit is an electrical circuit that distributes power from a main power source to subsidiary circuits or loads. - Where a feeder supplies continuous loads or any combination of continuous and non-continuous loads, the minimum feeder conductor size should have an allowable ampacity not less than the non-continuous load plus 125 percent of the continuous load. - The minimum feeder conductor size should have an allowable ampacity not less than the maximum load to be served after the application of any adjustment or correction factors.
- Group Motor ProtectionTwo or more motors, or one or more motors and other loads may be protected by the same branch circuit overcurrent protective device if: (a) All motors are 1Hp or less, protected at not over 20A at 120V or at 15A at 600V or less, the full load amp rating of each motor does not exceed 6 amps, the device rating marked on the controller is not exceeded.(b) The complete assembly of properly sized branch circuit overcurrent protective device, controller, and overload devices is tested, listed, and marked for a group installation.
- Individual Circuit for Motor Load- Motors are by far the most important pieces of equipment in the machine tool and panel building industry.Basically for all motor circuits the 4 functions are required:? Disconnect (main switch - Some additionally provide a means to disconnect the branch circuit for maintenance and safety purposes.)? Short-circuit protection? Operational switching (contactor)? Overload protection.
- Heater and lighting load circuitsHeater loads:The branch circuit protection is sized (exceptions for larger heater loads):1. Not less than 125 % of the heater load,2. Not more than 60 A, and not larger than the ampacity of the field wiring to the heater load.Controllers are sized to the heater full-load rating using the controller’s general-purpose amp rating or resistive load rating.Lighting loads:The branch circuit protection for standard-duty incandescent lamp holders or fluorescent ballasts 1. Should not exceed 20 A, and2. Should not exceed the ampacity of the anticipated field wiringThe controllers are sized to the specific lighting ratings.
- Power circuit wiring in the feeder and branch circuits.All conductors in the power circuit should be labeled at the termination point with letters or numbers corresponding with the wiring diagram provided in the control panel.For single loads, the wiring conductors should be sized for an ampacity of 125% of the full-load current.For multiple loads, such as multiple motors or a motor with other loads, the wiring is sized based on the sum of 125% of the largest motor Full Load Amperage, plus the sum of the other full-load currents of the remaining loads.
