Overload principle full#
Direct heating is used to supply full current to the motor using an overload relay, also known as an OLR. The function of this thermal overload relay depends mainly on the heating property of the bimetallic strip. Magnetic overload relays are classified into two types, electronic well as dashpot. This relay is usually used in an area where extreme changes in ambient temperature are displayed.
The main difference between a thermal overload relay and a magnetic relay is that the magnetic relay does not respond to the ambient temperature. As the core rises too much it then trips the set of attachments to the apex of the relay. The arrangement of the current inside the coil pulls the core. This can be made from a variable magnetic core inside the relay coil that holds the motor current. Which is generated by the flow towards the motor. The magnetic overload relay is operated by finding the strength of the magnetic field. Thermal overload is classified into two types of solder pot as well as a bimetallic strip. Thus the circuit should be overloaded for the entire period before it breaks. This motor is evenly designed to calculate the heating profile if the overload occurs even for a moment. However, most circuit breakers disrupt the circuit.
This relay relates to the circuit breaker as well as the application in construction. Once a maximum current is supplied to the motor circuit, the relay opens due to the modified temperature of the motor relay, otherwise, it detects the overload current depending on the type of relay. To achieve this, the relay involves an NC relay. When the motor uses excessive current for an extended period of time. And this is mainly designed to cut power. When the current exceeds the set value the bimetallic bar starts to heat up and then it turnsĪ thermal type relay is a protective device. In a motor circuit, this is designed in such a way that current can flow through its poles in a motor. The working principle of an overload relay depends on the electro-thermal properties within the bimetallic strip. If any contactor tries to push the start switch to turn off the switch, the motor will not start.Īlso Read: Buchholz Relay in Transformers | Construction of Buchholz Relay | Working Principle of Buchholz Relay | Applications of Buchholz Relay Overload Relay Working Principle: For example, the overload relay explores into the bimetallic relay, then the NC (normally closed) bimetallic connections will unlock the circuit until this strip cools. The main feature of this relay is that it prevents the motor from starting immediately. The Class 10, Class 20, and Class 30 overload relays can be found corresponding to 10 seconds, 20 seconds, and 30 seconds. The class of overload relays is classified into three types based on the duration of the relay exploration. Whenever the flow to the motor is higher than what is charged for the heater, the overload is detected after a few seconds. When this strip is heated to a certain temperature then this strip can give enough turns to break this circuit. The design of this relay uses two different types of metal strips and these straps can be interconnected as well as expand at different rates when heated. Although there are many types of overload relays available in the market, the most widely used rally in the market is the “bimetallic thermal overload relay”. The connection diagram of the overload relay is shown below and the connection of the overload relay symbol looks like two opposite question marks otherwise the overload relay function like the ‘S’ symbol is discussed.
Overload principle series#
The connection of this relay is made in series and placed between the motor and the contactor to prevent the motor from restarting during overload. When the heater gets too hot it is unlocked. The design of the overload relay can be done with the heater.
As well as when the heat detection device in the relay receives a fixed temperature it breaks the current.
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