Join 60,000+ competitive exam aspirants
or with email
Your Cart
Subtotal₹0
Total₹0
Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
Join 60,000+ competitive exam aspirants
Rated burden of relay in AC is given by
Voltage
Ampere
VA
None of above
VA
Quick Summary: The rated burden of a relay refers to the power consumption required for its operation at the rated current or voltage. Since relays involve electromagnetic coils (inductive load), this power is measured in Volt-Amperes (VA), representing the product of rms voltage and rms current.
The rated burden of a relay refers to the power consumption required for its operation at the rated current or voltage. Since relays involve electromagnetic coils (inductive load), this power is measured in Volt-Amperes (VA), representing the product of rms voltage and rms current.
S=Vrms⋅Irms — The definition of apparent power in VA.
S=P2+Q2 — Relationship between Apparent, Active, and Reactive power.
A relay is essentially an electromagnetic actuator. When energized, it consumes complex power (S=P+jQ), where P is the active power consumed by the copper losses and Q is the reactive power consumed by the magnetic field in the coil. The total apparent power consumed, S=V⋅I∗, is expressed in VA.
The relay burden must be low to prevent overloading the secondary of the Instrument Transformers (CT/PT).
Relays are inductive loads; thus, they consume reactive power alongside active power.
The burden is typically specified at the relay's rated current (for overcurrent relays) or rated voltage (for overvoltage relays).
Ensures compatibility with Instrument Transformers.
Provides a standardized metric for protection system design.
High burden leads to increased secondary circuit voltage drops.
Higher burden increases the saturation risk of Current Transformers.
Relay coordination studies.
Selection of CT/PT ratios and accuracy classes.
Standard values are usually mentioned in the relay datasheet.
Option A (Voltage) and B (Ampere) are incomplete units as they do not account for the phase angle between voltage and current.
C is correct — The rated burden of a relay is defined as the apparent power consumed by its coil, measured in Volt-Amperes (VA).
Always ensure the total VA burden of all relays connected to a CT secondary is within the CT's rated burden, or it may lead to secondary saturation and protection malfunction.