Thermal overload relays are very useful safety devices. They work in a way that is similar to that of fuse. The difference is that when the current passing through the fuse blows, the flow of electricity through the fuse must be shut off immediately. This way, you can prevent a fire from starting in case there is a short circuit in your circuit. Usually, thermal overload relays consist of a normally open (NC) thermal relay. It is used as a secondary device in the circuit to reduce the level of thermal energy passing through thermal overload relay.
There are several types of thermal overload relays. Some are built in load current protection circuits. Some are built in thermal switch protection circuits. Still some are designed for automatic switching function. The various types of the device are classified depending on the load currents passing through them.
There are different types of thermal overload relays available for every type of electrical appliance. They are available in two types. One is designed for a low-fuse condition and the other for a high-fuse condition. Low-fuse relays do not need any type of thermal switch or thermal cut-off switch. However, they will turn on and off based upon the setting value of the thermal cut-off switch.
There are three main contacts in thermal overload relays. The contacts that are in the hot and neutral position are called hot contacts, the neutral contacts and the cold contacts. These three contacts switch on and off based on the temperature compensation that is present in the circuit.
You have to pay close attention to the basic operation of the thermal overload relay figure 2. It uses a bimetallic sheet that is heated to its melting point. When a current is applied, the bimetallic sheet is moved to its cold spot and stays there until the current is removed. The current then flows through the conductors to the third contact.
The figure 2 thermal overload relay is normally closed when the load (the current) on the device reaches the predetermined threshold. The reason why the device is normally closed is because the thermal expansion value of the bimetallic sheet is exceeded. The thermal expansion value is typically measured in units of amperes per square inch.
Now, let us discuss the working of this thermal overload relay. When the high current flowing through the system reaches the thermal limit, the process of thermal expansion will occur. As the thermal expansion occurs, the amount of heat generated by the conductors rises above the level of the spring resistivity. The current flowing through the system will now exceed the maximum allowable value and will continue to rise causing overheating.
To prevent the thermal overload relay from failing you can prevent the thermal overload condition from developing. This can be done in a number of ways. You can either install a trip device such as described above, or a thermal barrier between the two power contacts on the relay. The thermal barrier is usually made of Teflon tape or some other insulating material. The only disadvantage of this method is that a regular inspection will need to be conducted on the relay every six months to a year to keep it in good operating condition.
One very simple way to avoid triping is to avoid switching on the power. There are several different ways in which this can be achieved. Firstly, if your heater has been switched on but has not yet reached full temperature, then there could be a short circuit somewhere in your heater. If you want to reset thermal overload relays, then you should switch off your power source and wait for the heater to reach the temperature that it was designed to. If after a few minutes the device comes back on, then the break is simple, but you should check carefully that there was no short circuit in place.
Of course, if your system is designed to handle extreme temperatures then it is probably worth buying a system that offers built in thermal overload relays. These types of devices are usually incorporated within the main supply rails. This means that your power supply needs to be of a sufficient quality and capacity to actually allow the device to function. You do have to remember that if a thermal overload current should actually pass through a part of the power cable then there will be a short circuit. In order to prevent this type of occurrence, it is a good idea to purchase a device that can offer protection against the excessive thermal overload currents. This means that you need to make sure that the power cable is sufficiently strong and wide enough so that it can actually carry the current to its destination.
When selecting a thermal overload relay that will provide protection against the extreme temperatures that your equipment can withstand, you have several different options. A number of different manufacturers offer their own range of products. It can be worthwhile contacting them to find out more about the range they have available. They should be able to provide you with a lot of information on the working principle of the thermal overload relay, including its characteristics and what the manufacturer can guarantee in terms of its performance. This should help you decide whether their product is the right choice for your application or not.