Security Systems & Electronic Access Flashcards

Which electric locking device is described as 'fail-safe' because it unlocks when power is lost?

Answer: Magnetic lock

A magnetic lock needs continuous power to hold, so it releases when power is removed.

What is the primary purpose of a request-to-exit (REX) device on an access-controlled door?

Answer: To let a person leave without triggering a forced-door alarm

A REX shunts the door-position alarm and releases the lock when someone exits legitimately.

A door position switch (DPS) on an access-controlled door primarily reports what?

Answer: Whether the door is open or closed

A DPS is a contact that monitors the open/closed state of the door.

Which wiring protocol is commonly used between card readers and access control panels and sends data on D0 and D1 lines?

Answer: Wiegand

Wiegand uses two data lines (D0 and D1) to send credential bits to the panel.

What is a 'held open' alarm in an access control system?

Answer: The door remains open longer than the programmed time

A door held open alarm triggers when the door stays open beyond its allowed time.

Why is a diode or MOV often installed across the coil of an electric strike or maglock?

Answer: To suppress voltage spikes when the coil de-energizes

Inductive coils generate back-EMF spikes that can damage electronics, and suppression devices absorb them.

Which power supply feature lets an access control system keep working during a power outage?

Answer: Battery backup (UPS or standby battery)

Standby batteries or a UPS keep the panel, readers and locks operating during outages.