A momentary low voltage, from 1 cycle to a few seconds, is a: 

Answer options:

A. spike
B. blackout
C. sag
D. fault

C

A momentary low voltage is a sag.A synonym would be a dip. Risks to electrical power supply: POWER FAILURE - Blackout: complete loss of electrical power Fault: momentary power outage - POWER DEGRADATION - Brownout: an intentional reduction of voltage by the power company. Sag/dip: a short period of low voltage POWER EXCESS - Surge: Prolonged rise in voltage Spike: Momentary High Voltage - In-rush current: the initial surge of current required by a load before it reaches normal operation.Transient: line noise or disturbance is superimposed on the supply circuit and can cause fluctuations in electrical power Refence(s) used for this question: Harris, Shon (2012-10-25). CISSP All-in-One Exam Guide, 6th Edition (p. 462). McGraw-Hill. Kindle Edition.