17/08/2022 for Ultatek Soft starters for electric motors are solid-state systems that protect AC electric motors from damage caused by sudden power surges by limiting the large initial inrush of current associated with motor startup. They provide a smooth ramp-up to full speed and are used only during starting (and stopping, if equipped). Here you will find a comprehensive guide on the selection, use, and application of soft starters, where we will review: What is a soft starter for electric motors? How does a soft starter for electric motors work? What are the most common applications for soft starters in electric motors? The advantage of using soft starters for electric motors in industry is their ability to gradually increase voltage to the motor, which reduces the initial current surge when the motor starts. This soft start process minimizes mechanical stress on the motor and connected equipment, prolongs their lifespan, and reduces the likelihood of electrical system disturbances like voltage dips. It also leads to energy savings due to lower starting current draws. What's the difference between using a soft starter and a variable frequency drive? When to use a soft starter or a variable frequency drive? The most common reasons for soft starter failures in electric motors are: What is a soft starter for electric motors? Soft starters are devices that can be added to an AC electric motor to allow the motor to use a different starting method. The ultimate goal is to reduce the stress placed on the motor during the typical ignition phase. To achieve this, soft starters will begin to apply slowly and gradually increasing voltages to the motor, allowing for a smooth ramp-up of power rather than a power surge that could cause damage to the motor and the machine as a whole. While most starters for electric motors involve a surge of electrical currents hitting the motor, a soft starter offers a smooth, constant linear ramp-up of power. This reduces the overall strain on the motor's circuits, resulting in a healthier machine that's less prone to breaking down quickly. Depending on the soft starter model, some have the ability to adjust the starting voltage and how long it takes for the motor to reach full power. How does a soft starter for electric motors work? In general terms, soft starters for electric motors control the amount of voltage that flows through the motor circuits to limit motor torque. This allows the soft starter to reduce voltage and then gradually decrease it to allow for a smooth progression of current. In addition to this, some models of soft starters for electric motors can use solid-state devices. These devices are another means of controlling the amount of electrical current that is allowed to flow through the motor. This allows the soft starter to control the current in three separate and distinct phases to allow for more precise levels of control. Many electric soft starters also utilize a series of silicon-controlled rectifiers (SCRs), or thyristors, to limit voltage to a more manageable amount for the motor when it first begins to start. These SCRs have an ON state, in which they allow current to flow, and an OFF state, in which they control and limit electrical current. When the machine is powered on, these SCRs are triggered, restricting the voltage and then relax as the machine reaches full power. This keeps the motor heat low and reduces overall strain. Although soft starters for motors are an example of a possible soft-start solution, they are not the only solution available. There are also mechanical options that rely less on electrical current and more on physical and mechanical solutions. Mechanical soft starters are based on clutches and various couplings that use fluids, steel grit, or magnetic forces to reduce the amount of torque on the motor. This limits the allowable strain on the motor and allows it to start more smoothly and easily. What are the most common applications for soft starters in electric motors? It is important to know when a soft starter is needed and if it is necessary for all motors or only for some machines. The reality is that no motor absolutely needs a soft starter, however, many motors will greatly benefit from the installation of a soft starter, as certain motors are more susceptible to breaking and wearing out due to excessive amounts of electrical current during their startup phase. Here are some of the common applications where soft starters facilitate the startup process: Starters for pumps In many pumps, there is a risk of voltage surges. By installing a soft starter and gradually feeding electrical current to the motor, this risk is greatly reduced. Conveyor belt starters Sudden starts can cause problems with conveyor belts, as they can jolt and become misaligned. Conventional starting also adds unnecessary stress to the belt's drive components. By installing a soft starter, the belt will start up more gradually and have a higher chance of staying properly on track. Starters for fans and similar systems In belt drive systems, potential problems are similar to those encountered with conveyor belts. Sudden and jerky starts put the belt at risk of coming off its track. A smooth start corrects this issue. The advantage of using soft starters for electric motors in industry is their ability to gradually increase voltage to the motor, which reduces the initial current surge when the motor starts. This soft start process minimizes mechanical stress on the motor and connected equipment, prolongs their lifespan, and reduces the likelihood of electrical system disturbances like voltage dips. It also leads to energy savings due to lower starting current draws. While it depends on the motor itself, investing in soft starters for electric motors is worthwhile. Here are some of the main benefits of installing a soft starter on a motor: Energy reduction Reducing the amount of energy machines require is always an ideal goal, and soft starters contribute to this. With conventional starting, the motor immediately begins to consume the maximum amount of energy and continues to do so for the entire time the motor is running. With a soft start, the voltage gradually builds up until it reaches its maximum, which means less energy is generally consumed. Lower risk of overvoltage When maximum voltage immediately hits the motor to start it, there's always a chance of circuits overloading and the motor experiencing a voltage surge. A soft starter is an excellent protective measure against voltage surges. Instead of throwing all the power to the circuits at once, the voltage ramps up gradually. Adjustable acceleration time Soft starters for industrial motors come equipped with this option, which provides a significant advantage because you can choose the amount of time you want the motor to spend ramping up. If it is known that an engine or machine is prone to power surges or is old and worn, you can configure it to take a little longer to start. If, on the other hand, a machine is known to be robust and reliable, it can be expected to start faster. In any case, this flexibility and customization is a huge advantage. Potential increase in hourly starts A motor requires a lot of energy to start conventionally. This means that, depending on the machine, it may not be able to start an excessive number of times in a specific hour. However, with a soft start, the motor will use less energy each time it starts, meaning it will be able to start more often. Overheating risk reduction The large surge of energy associated with a conventional start can sometimes cause the engine to overheat. This overheating can be harmless, but it can also cause the engine to temporarily shut down and can even cause long-lasting damage to the engine. A soft start does not involve this initial burst of energy. Instead, a gentle surge of electricity is supplied to the motor, which greatly reduces the risk of overheating. Improving operational efficiency Conventional starters can work perfectly sometimes. Other times, however, they can cause problems. The motor can overheat, it can malfunction, and there can be a power surge. Given that the risk of these problems is eliminated or greatly reduced with a soft start, a machine will be able to operate more efficiently and with less risk of problems and damage. Longer service life It is impossible to guarantee something like a machine's lifespan, but it is very likely that by adding a soft starter to a machine, you are extending its lifespan. This makes a lot of sense because the risk of many incidents and accidents that can end a machine's lifespan is being reduced. Ultimately, the advantages of soft starters for electric motors help to: Reduce the risk of wear and damageBecause operations start smoothly and under control, overall wear is reduced, making conveyor systems, cranes, main engines, and pumping systems last longer and require less service overall. Reduce the risks of voltage surges or overloads during operationA soft starter helps limit transient stresses, while protecting against sudden surges that accompany both normal operation and power outages. Reduce risk to personnel and limit personal injuryLarge equipment can be very dangerous, and there's always a risk when using it. By including a motor starter that controls electrical loads and achieves smoother, more predictable operation, it's an excellent way to reduce the risk of personal injury in the workplace. What's the difference between using a soft starter and a variable frequency drive? A variable frequency drive has some similarities to a soft starter, but there are enough differences to put it in a class of its own. VFDs, or variable frequency drives, are motor control devices that control the speed of an AC induction motor. This means it can control the motor's speed during starting and stopping cycles, as well as during the ordinary running cycle. Based on this, it's easy to see the similarities between a Variable Frequency Drive (VFD) and a soft starter. Both have a way to control the amount of power going to a motor during startup, and both can help prevent things like voltage surges and problems during startup. However, they differ in the method they employ to achieve this goal. When to Use a Soft Starter or a Variable Frequency Drive (VFD) A variable frequency drive is usually preferred if the main objective is energy saving. This is because a VFD not only limits the motor's speed during the startup phase but can also help control the speed during the ordinary operating cycle, as well as during the shutdown phase. This makes them ideal for reducing power when it's not needed, which translates to lower overall energy expenditure. Variable frequency drives are also a good option in situations where it is important to be able to control the speed and proper operation of a machine. Applications of Variable frequency drives in multi-pump systems for water control They fit this description because the constant speed of these devices can be controlled, and they can be prevented from experiencing any unexpected power surges. The most common reasons for soft starter failures in electric motors are: Soft starters for electric motors, like any other piece of equipment or machinery, can break down or fail. Although the soft starter should be in good working condition for the foreseeable future, you never know what might happen. The reasons why soft starters fail could be associated with one of these problems: Too hot: An overheated machine can cause all sorts of problems. A machine with a soft start is less likely to overheat than one with a conventional start, but it's still possible. Too much strain: Since the purpose of a soft starter is to limit the amount of electrical current at the beginning, this is unlikely to happen. However, if a higher-than-usual voltage reaches your motor during startup, it could cause problems. Too much current: This is a similar problem to excess voltage. If too much current flows into the motor initially, it could overload the circuits and cause a malfunction. Soft starters make motors and machinery less prone to malfunction and do a magnificent job of protecting them from things like overheating and power surges. They also contribute greatly to extending the lifespan of most motors. All in all, they are very reliable and provide an extra layer of safety and protection for your motors. We are authorized distributors of soft starters for TOSHIBA electric motors in Mexico, Contact one of our technical advisors now.
