Electronic overloads sense the load current and the heating effect on the motor is computed. If an overload condition exists, the sensing circuit interrupts the power circuit. |
C The tripping current can be adjusted to suit the particular application. |
C Electronic overloads often perform additional protective functions such as ground fault and |
phase loss protection. |
Fuses |
Fuses have limited application as the primary means of overload protection for motors but can be effectively used to provide back up overload protection. |
• Single-element fuses are not designed to provide overload protection. |
C Their basic function is to protect against short circuits and ground faults. |
C If sized to provide overload protection, they would blow when the motor starts due to high |
motor inrush current. |
• Dual-element fuses can provide motor overload protection, but they have to be replaced |
when they blow which can be a disadvantage. |
• There is a risk of single-phasing damage to the motor when only one fuse blows unless |
single-phase protection is provided. |