Control Panel U blog

Summary: Circuit breakers are sized according to rules established by codes and standards. For common applications, a 250% x motor FLA maximum size limitation is used.  However, this is different when drives are used, or when special circuit protection types are used. Introduction Circuit breakers are commonly used in circuit protection of motor circuits.  Size it wrong and you could end up with nuisance tripping, or even worse insufficient circuit protection. Sizing a circuit breaker for a motor load isn't overly complicated but there are some rules to follow, and a few things to check.  This article simplifies how circuit breakers are sized for motor loads in the US. What can go wrong? Do you ever wonder why a breaker isn't sized to match the motor full load amp (FLA) rating?  What would happen? Likely your circuit breaker would trip when the motor is turned on.  Electric motors have a higher current at start up.  This is sometimes referred to as inrush ....

Summary: The choice of overcurrent circuit protection depends on various factors.  The right choice depends on the application and functions required. Introduction Many, many years ago, there were two overcurrent protection options... breakers and fuses.  Over time new circuit protection options have appeared on the scene.  Millions of electric motors are in operation in the US, and each one needs overcurrent protection.  These circuit protection devices play a very important role, not only in opening motor circuits, but also in how the control panel is designed, built, installed, and operated.  In this article we will cover the main options, their main benefits and disadvantages, as well as where they often function the best. What are the options? There are several different types of circuit protection used in motor control circuits, each bringing its own mix of value and use.  The following are the most popular: Fuses - These devices use a self-sacrifici...

Summary: You may be new to industrial controls and automation, but don't let that diminish you participation and ability to be confident.  By setting the right expectations and building a technical resource network, you have all you need to speak confidently about industrial controls. Introduction Are you a recent graduate about to start a new job? Or possibly you are changing industries and are new to industrial automation.  It can be very intimidating venturing into a new space where we don't have experience.  We have all been there. A lack of confidence shows up in your actions.  Humans seem to subconsciously detect when others lack confidence, which may result in some doubt in your response.  Confidence has a big impact on whether or not we perceive someone as trustworthy or an authority. You don't have to enter into a new job or a new industry as an expert before you can talk with others.  The good news is that you can speak confidently, despite h...

Which contactor is better - IEC, NEMA or Definite Purpose? Summary: The choice of contactor type depends most on who is making the decision, and what they value the most.  NEMA = ROBUST, Definite Purpose = "budget friendly", and IEC = versatile. There are reasons for three different types of contactors, and there are reasons one makes more sense than the other... depending on who you ask. What makes each type unique? NEMA - This type is the "tank" of the contactor world.  It is big, has large contacts that makes it capable of handling even severe applications.  NEMA devices are also easy to maintain - repair it and put it back into service.  I used to work in tech support for a market leader of NEMA motor control, and it was not unusual to hear of NEMA units operating for 40 years. Definite Purpose - As the name implies, this type has an intended use, and performs in that use well.  It has an attractive price point, but don't expect too much more of it though. D...

Summary:  With so many different contactor brands available in the US, which one is right for you?  This blog identifies the product features and non-product features likely to make a difference in your equipment for general applications in the US. There are many brands of contactors in the US.  Who has the time to evaluate them all? Most controls engineers do not, and often learn the good and the bad by experience.  Here are a few things to really pay attention to and a few that are not super critical. What's likely NOT critical to evaluate (i.e. what's fairly common across all offers): Physical Size - they are all basically the same width. Sizes up to 20HP are 45mm wide, 25 to 40HP are 55mm wide. Some minor differences on height and depth but overall these are mostly negligible once installed in the control panel. Approval Certification - Almost all brands sold in the US have UL HP ratings and a General Purpose or Continuous Current amp rating. Coil voltage option...

Summary: Sustainability is an objective that more and more companies desire to achieve, but it is not always easy to implement. The good news is that there is a simple substitution that can be made in control panels that will reduce CO2 emissions over the life of the equipment or machinery. What is the Secret? 🤯 The technology that enables this achievement is the electronic control coil on the contactor. Traditional contactors use a coil bobbin to generate a magnetic field when energized, which pulls the contacts together and completes the circuit to the electric motor. This does the job but requires continuous energy consumption while the contactor is operating. Contactors with electronic coils consume less energy. A circuit board more efficiently manages the magnetization and hold-in consumption. For example, a common 9 amp contactor with an electronic coil may consume 1.4 VA in the hold-in state, whereas a 9 amp contactor with a traditional bobbin would coil may consume 8 VA in...

  Summary: Have you ever realized after the fact that a higher SCCR is needed? In this blog we will discuss the use of fuses, and why this may not fix insufficient SCCR. Wha t's the problem? The NEC requires that control panels have sufficient SCCR. This is the amount of short-circuit current a control panel is rated to endure should a short-circuit occur. There could be a lot of available short-circuit current or a little. It all depends on what the electrical system can deliver. Usually, the cause for the panic comes when it is discovered that a higher SCCR is needed AFTER the control panel is built and installed in the field. A simple quick fix would be ideal in this situation. Often the idea of adding a fuse comes up. Why add a fuse? A fuse in the simplest terms is a strip of metal, usually copper or some alloy, in a protective tube that melts very fast in the event of a steep rise in current, like a short circuit. This quickly opens the circuit and halts the damaging h...