# Understanding The Cutler Hammer Overload Relay Chart

Cutler-Hammer overload relays are designed to protect motors from being overloaded. The relays are designed to detect when the current draw of a motor exceeds a predetermined level for a given time interval. If there is an overload, the relay will trip and shut off the motor. Cutler-Hammer overload relays are used in a variety of applications such as industrial, commercial, and residential.

Before you can use a Cutler-Hammer overload relay, you must first understand how to interpret the Cutler-Hammer overload relay chart. The chart is a graphical representation of the amount of current that a motor can safely handle without tripping an overload relay. The chart is divided into four sections: phase, type, temperature, and current. In each section, the values are expressed in amperes (amps).

The phase section of the chart indicates the number of phases for a particular motor. Most motors are either single phase or three-phase. Single phase motors have one hot wire, while three-phase motors have three hot wires. The type section of the chart indicates the type of motor, such as induction or synchronous. The temperature section indicates the maximum ambient temperature for the motor. The current section indicates the maximum current that can be safely drawn by the motor.

## How to Use Cutler Hammer Overload Relay Chart

Now that you understand the Cutler-Hammer overload relay chart, you can use it to select the correct size of overload relay for your motor. To do this, you will need to know the phase, type, temperature, and current of your motor. Once you have this information, you can refer to the chart to determine the maximum current that the motor can safely draw without tripping an overload relay.

For example, let’s assume that you are selecting an overload relay for a single-phase motor. The motor is rated at 240V and has a maximum ambient temperature of 40°C. The current draw of the motor is 15A. Referring to the chart, you can see that the maximum current that the motor can safely draw is 20A. Therefore, you would select an overload relay that is rated for 20A.

When selecting an overload relay, it’s important to remember that the current rating of the relay should be slightly higher than the current draw of the motor. This will help ensure that the overload relay does not trip during normal operation. It’s also important to make sure that the overload relay is UL listed and CSA approved.

### Cutler Hammer Overload Relay Chart

Below is an example of a Cutler-Hammer overload relay chart. This chart is for a single-phase motor rated at 240V.

Phase Type Temp. Current
1 Induction 25°C 20A
1 Induction 40°C 17A
1 Synchronous 25°C 17A
1 Synchronous 40°C 15A

By using the Cutler-Hammer overload relay chart, you can select the proper size of overload relay for your motor. This will help ensure that your motor is protected from overloads and keeps your system running smoothly.

## Conclusion

The Cutler-Hammer overload relay chart is an important tool for selecting the correct size of overload relay for a motor. By understanding how to read and use the chart, you can ensure that your motor is protected from overloads and keeps your system running smoothly. As with any system, it’s important to consult a qualified electrician or engineer if you have any questions or concerns regarding the Cutler-Hammer overload relay chart.