Are Solid State Relays More Reliable
When choosing components for any machine in manufacturing, cost is always a consideration.
A large reason manufacturers choose electromagnetic or mechanical relays is because they’re usually the cheapest option. Convincing buyers to purchase the more expensive solid state relays comes down to proving they’re cheaper in the long term. This is due to their superior reliability. Obviously, if buyers are going to be convinced, they will need to know the answer to just why are solid state relays more reliable. It is almost entirely due to not having any moving parts. Here are some of the ways this works…
So Many More Cycles
Solid State Relays (SSRs) are the ideal choice for high volume switching applications. Simple heating applications using normal resistance type elements can be switched on and off many times per minute to maintain temperature. Mechanical relays with moving parts have contacts that will wear out with repeated use. This will happen regardless of the type of plating used on the contacts as every material will erode eventually. Because SSRs don’t have any parts to wear out or erode, they can perform infinite switching cycles during their life cycle. A typical mechanical relay can have an electrical lifespan of up to 1.3 million operations, which sounds a long time. If you take a slow heating process that has an ON/OFF cycle time of every 8 seconds, the relay will last for 120 continuous days. Maybe not so long then. That means you could be replacing the relay three times a year. So, although the average relay contactor may initially cost a 3rd of the price, it could cost you 10x more over the average lifespan of the SSR. Also, and more importantly, using an SSR can help reduce machine downtime due to relay/SSR changeover by a staggering 95%.
The lack of moving parts in an SSR means they are less vulnerable to contaminants such as dirt and moisture. This means they can be used in many more challenging applications. The effects of outside influences such as temperature, vibration and shock are also reduced due to the SSR’s lack of contacts and moving parts. They are also more resistant to electromagnetic currents.
Because SSRs allow current through based on a small gate current being applied rather than a contact being physically made and broken, they switch silently. This is important in noise sensitive applications, but it is also important in terms of electrical ‘noise’. Sensitive automation systems such as temperature controllers can suffer interference from electromagnetic relays arcing when the contacts come together. SSRs completely ameliorate this problem and only require a very small current to switch them from open to closed. Another benefit to SSRs is their superior inductive load protection. Damage in circuits can occur when the power in an AC circuit is broken and the energy surges in the direction of the source. With mechanical switches, this can result in pitting, arcing and failure eventually. SSRs are designed to prevent this from happening.
Another reason SSRs are extremely reliable is because they can switch so quickly. This level of fine control means that heating elements can be kept at the exact temperature, avoiding overheating and power surges, prolonging the life of heating elements.
Whether you are using an SSR or a thyristor to control the power in your machines, getting the right one for the job is essential. That is why our team of experts can assess your requirements and make recommendations, so you get the best power control solution for your machine. To speak to someone about your requirements, please get in touch on 01323 811 100.