Types of overcurrent and protective devices in AC systems

What is overcurrent?

• Excess of voltage in an electrical circuit

• Excess of current in an electrical circuit

• Excess of resistance in an electrical circuit

• Excess of power in an electrical circuit

Which of the following is not a type of overcurrent?

• Overload overcurrent

• Voltage overcurrent

• Ground-fault overcurrent

• Short-circuit overcurrent

What is the main cause of short-circuit overcurrent?

• Overloading the circuit

• Cross-connection of current-carrying conductors

• Ground fault

• Arc fault

Where should overcurrent protection for conductors and connected load be installed?

• At the point of origin of the conductors

• Downstream

• At the load side

• Upstream

Which type of relay operates when the current reaches its pick-up value and a predetermined time?

• Definite-time Overcurrent Relay

• Instantaneous overcurrent relay

• Inverse Definite Minimum Time Relay

• Inverse-time overcurrent relay

What is the main difference between Ground-fault overcurrent and Short-circuit overcurrent?

• Ground-fault overcurrent involves one of the circuit conductors and the circuit ground

• Short-circuit overcurrent involves one of the circuit conductors and the circuit ground

• Ground-fault overcurrent has higher magnitude compared to Short-circuit overcurrent

• Short-circuit overcurrent only occurs in AC systems

What is the purpose of Circuit Protection in overcurrent systems?

• To protect conductors and connected load from overcurrent

• To regulate the voltage in the circuit

• To protect equipment by opening when it detects short-circuits or ground faults

• To provide power to the circuit

Which relay has no intentional time delay for operation?

• Inverse Definite Minimum Time Relay

• Definite-time Overcurrent Relay

• Instantaneous overcurrent relay

• Inverse-time overcurrent relay

Where should Overload protection be located in an electrical power distribution system?

• At the load side

• Upstream

• Downstream

• At the point of origin of the conductors

What is the characteristic of Inverse-time overcurrent relay?

• Operating time is set and programmed

• Operating time is inversely proportional to the fault current

• Operating time depends on the magnitude of the operating current

• Operating time is always constant