Allen Bradley starters are commonly used in industrial applications to control the operation of motors. These starters help in starting, stopping, and protecting the motor against overload and short circuits. The wiring diagram of the Allen Bradley starter is a complex schematic that can be daunting for beginners. In this article, we will explain the wiring diagrams of Allen Bradley starters in a simple and easy-to-understand manner.
Understanding Allen Bradley Starter Wiring Diagrams
The wiring diagram of an Allen Bradley starter consists of several components, including the power circuit, control circuit, overload relay, and contactor. Each of these components plays a crucial role in controlling the operation of the motor. Let’s take a closer look at each of these components:
Power Circuit
The power circuit is responsible for supplying power to the motor. It consists of a three-phase AC supply that is connected to the line terminals of the starter. The power circuit also includes fuses or circuit breakers that protect the motor against short circuits and overloads.
The power circuit also comprises a contactor that connects and disconnects the motor from the power supply. The contactor is controlled by the control circuit, which we will discuss in the next section.
Control Circuit
The control circuit is responsible for controlling the operation of the contactor. It includes a set of pushbuttons and pilot devices that allow operators to start, stop, and reset the motor. The control circuit also includes a control transformer that converts the three-phase AC supply to a lower voltage.
The control circuit also comprises a set of control relays that energize and de-energize the contactor. The control relays are controlled by the pushbuttons and pilot devices. The control circuit also includes overload relays that protect the motor against overload conditions.
Overload Relay
The overload relay is a protective device that is connected in series with the motor. It senses the current flowing through the motor and trips the contactor if the current exceeds the rated value. The overload relay also includes a thermal element that protects the motor against overheating due to prolonged overloads.
Wiring Diagrams for Allen Bradley Starters
Wiring diagrams for Allen Bradley starters can be complex and may vary depending on the type and model of the starter. However, there are some basic principles that apply to all starters. Let’s take a closer look at some of the commonly used Allen Bradley starter wiring diagrams:
Single-phase Starter Wiring Diagram
The single-phase starter wiring diagram is used for motors that require single-phase power. It consists of a single-phase AC supply that is connected to the line terminals of the starter. The wiring diagram also includes a control transformer that converts the single-phase AC supply to a lower voltage. The control circuit comprises a set of pushbuttons and pilot devices that control the operation of the contactor.
| Component | Wire Color | Terminal Number |
|---|---|---|
| AC Supply | Black | L1 |
| Control Transformer | Red | X1 |
| Contact | Blue | T1 |
| Pushbutton | Green | Y1 |
In this wiring diagram, the black wire is connected to the L1 terminal of the starter, and the red wire is connected to the X1 terminal of the control transformer. The blue wire is connected to the T1 terminal of the contactor, and the green wire is connected to the Y1 terminal of the pushbutton.
Three-phase Starter Wiring Diagram
The three-phase starter wiring diagram is used for motors that require three-phase power. It consists of a three-phase AC supply that is connected to the line terminals of the starter. The wiring diagram also includes a control transformer that converts the three-phase AC supply to a lower voltage. The control circuit comprises a set of pushbuttons and pilot devices that control the operation of the contactor.
| Component | Wire Color | Terminal Number |
|---|---|---|
| AC Supply | Black, Red, Blue | L1, L2, L3 |
| Control Transformer | Yellow, Orange | X1, X2 |
| Contact | White, Black, Red | T1, T2, T3 |
| Pushbutton | Green | Y1 |
In this wiring diagram, the black, red, and blue wires are connected to the L1, L2, and L3 terminals of the starter, respectively. The yellow and orange wires are connected to the X1 and X2 terminals of the control transformer, and the white, black, and red wires are connected to the T1, T2, and T3 terminals of the contactor, respectively. The green wire is connected to the Y1 terminal of the pushbutton.
Frequently Asked Questions
What is an Allen Bradley starter?
An Allen Bradley starter is an electrical device that is used to control the operation of motors. It consists of several components, including the power circuit, control circuit, overload relay, and contactor. Allen Bradley starters are commonly used in industrial applications.
What is a wiring diagram?
A wiring diagram is a schematic representation of an electrical circuit. It shows the components and connections of the circuit in a simplified manner. Wiring diagrams are commonly used in electrical engineering and are essential for troubleshooting and maintenance.
Why is the overload relay important in Allen Bradley starters?
The overload relay is an important component in Allen Bradley starters as it protects the motor against overload conditions. If the current flowing through the motor exceeds the rated value, the overload relay trips the contactor and disconnects the motor from the power supply. The overload relay also includes a thermal element that protects the motor against overheating due to prolonged overloads.
What is a control circuit in Allen Bradley starters?
A control circuit is a set of components that controls the operation of the contactor in an Allen Bradley starter. It includes a control transformer that converts the AC supply to a lower voltage, pushbuttons and pilot devices that allow operators to start, stop, and reset the motor, and control relays that energize and de-energize the contactor.
What is a power circuit in Allen Bradley starters?
A power circuit is a set of components that supplies power to the motor in an Allen Bradley starter. It includes the AC supply that is connected to the line terminals of the starter, fuses or circuit breakers that protect the motor against short circuits and overloads, and the contactor that connects and disconnects the motor from the power supply.
