MIDTERM - PRE TEST

Which instrument is used to measure voltage, current, and resistance?

• Multimeter

• Insulation tester

• Clamp meter

• Voltmeter

Answer explanation

A multimeter is a versatile instrument that can measure voltage, current, and resistance, making it the correct choice. Other options like voltmeters and clamp meters have more limited functions.

What is the minimum insulation resistance allowed between conductors in a 230V circuit?

• 0.5 MΩ

• 1 MΩ

• 2 MΩ

• 5 MΩ

Answer explanation

The minimum insulation resistance required between conductors in a 230V circuit is 1 MΩ. This standard ensures safety and reduces the risk of electrical faults.

Which type of insulation tester uses a crank handle to generate voltage?

• Digital tester

• Analog meter

• Hand-cranked tester

• Solid-state tester

Answer explanation

The hand-cranked tester generates voltage through a manual crank handle, making it distinct from digital testers, analog meters, and solid-state testers, which rely on electronic components for voltage generation.

What type of suspension is common in solid-state insulation testers?

• Pivot and jewel

• Taut band

• Spring coil

• Magnetic balance

Answer explanation

Taut band suspension is commonly used in solid-state insulation testers due to its stability and accuracy. It allows for precise measurements by minimizing friction and enhancing the responsiveness of the device.

Which component protects multimeters from high fault currents?

• Glass fuse

• HRC fuse

• Circuit breaker

• Relay

Answer explanation

The HRC (High Rupture Capacity) fuse is designed to protect multimeters from high fault currents by interrupting the circuit quickly, preventing damage. Unlike glass fuses, HRC fuses can handle higher currents safely.

What should always be done before and after using a voltage tester?

• Charge the battery

• Test the tester

• Replace the probes

• Check the fuse

Answer explanation

Before and after using a voltage tester, it's crucial to test the tester itself to ensure it is functioning correctly. This step verifies that the tester provides accurate readings, ensuring safety during electrical work.

Which multimeter type is better at showing a changing value?

• Analog

• Digital

• Clamp

• Insulation tester

Answer explanation

Analog multimeters are better at showing changing values because they use a needle that moves in real-time, providing a visual representation of fluctuations. Digital multimeters display values numerically, which may lag behind rapid changes.

Which display is easier to read and usually more accurate?

• Analog

• Digital

• Clamp meter

• Test lamp

Answer explanation

Digital displays are easier to read due to their clear numerical output, reducing the chance of misinterpretation. They also provide more precise measurements compared to analog displays, making them generally more accurate.

What type of value does a typical voltmeter display for AC?

• Peak value

• Peak-to-peak value

• RMS value

• Average value

Answer explanation

A typical voltmeter displays the RMS (Root Mean Square) value for AC, as it represents the effective voltage that would produce the same power in a resistive load as a DC voltage of the same value.

What error occurs if the analog meter is not viewed directly from above?

• Overload

• Resolution error

• Parallax error

• Calibration error

Answer explanation

Parallax error occurs when the analog meter is not viewed directly from above, causing a misreading of the measurement due to the angle of observation. This is why it's crucial to align your line of sight with the scale.