Electronics and Electrical Safety Flashcards

When testing electrical safety with a safety analyzer, the 'patient lead to ground' leakage test measures current flowing from:

Answer: Applied parts to the equipment ground

Patient lead-to-ground leakage measures current that could flow through a patient from applied parts to ground, reflecting direct patient risk.

What is the function of a decoupling capacitor placed near an IC power pin?

Answer: Filter high-frequency noise on the supply rail

Decoupling capacitors suppress high-frequency transients and noise on the supply voltage rail, stabilizing IC operation.

An op-amp configured with the non-inverting input connected to a voltage divider and output fed back to the inverting input is functioning as a:

Answer: Voltage follower (buffer)

When the output feeds directly back to the inverting input with no other feedback components, the op-amp becomes a unity-gain voltage follower.

Which condition does a Line Isolation Monitor (LIM) detect in an isolated power system?

Answer: First fault to ground in the isolated circuit

A LIM continuously monitors the impedance from the isolated conductors to ground and alarms when the first fault reduces isolation below safe limits.

In a full-wave bridge rectifier with four diodes, the output ripple frequency relative to the AC input frequency is:

Answer: Double (2×)

A full-wave bridge rectifier conducts on both half-cycles, producing two output pulses per input cycle, doubling the ripple frequency.

According to electrical safety standards, the ground wire in a medical device power cord must be:

Answer: The same gauge as the hot conductor

The equipment ground conductor must be at least the same gauge as the current-carrying conductors to safely carry fault current.

Thermal runaway in a bipolar junction transistor (BJT) is caused by:

Answer: Positive feedback between temperature rise and collector current increase

As a BJT heats up, leakage current increases, raising collector current which generates more heat, creating a destructive positive feedback loop.