RELAY CO-ORDINATION

What is the purpose of relay coordination?

• To ensure proper relay settings and avoid maloperation
• To increase the voltage of the system
• To reduce the current of the system
• To increase the power factor of the system

What is the main criterion in relay coordination?

• Time-delay
• Voltage
• Current
• Power factor

What is the difference between primary and backup relays in a coordination scheme?

• Primary relays operate first and backup relays operate later
• Primary relays operate later and backup relays operate first
• Primary relays and backup relays operate at the same time
• There is no difference between primary and backup relays

What are the common methods used for relay coordination?

• Time-current grading, directional grading, and time-delta grading
• Voltage-current grading, directional grading, and time-delta grading
• Time-current grading, non-directional grading, and power factor grading
• Voltage-current grading, directional grading, and power factor grading

Which of the following is an advantage of using computer-aided relay coordination?

• Faster and more accurate than manual calculations
• Less expensive than manual calculations
• Does not require specialized software
• Can be done without knowledge of relay coordination principles

What is the purpose of using time-delay relays in coordination schemes?

• To avoid maloperation due to transient faults
• To provide backup protection
• To improve system stability
• To reduce the effect of harmonics