Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
18 Cards in this Set
- Front
- Back
|
3 types of measuring instruments |
Mechanical instruments Electrical instruments Electronic instruments |
|
|
General use of a mechanical instrument |
Used in stable/static conditions due to inability to respond to rapid dynamic movement (AC currents) |
|
|
General use of electrical instruments |
Am meters used to measure current due to low resistance when connected in series. |
|
|
General use of electronic instruments |
Multimeter, which has quick response times and can be used to measure a range of quantities |
|
|
Operation of digital instruments |
Sensor Processor Output |
|
|
Describe the operation process |
The sensor detects set quantity I.e current, volts etc. And sends the signal to the processor where it is digitised for calculation. Once calculation is complete it is output to the lcd screen for reading. |
|
|
4 measurements made using a multimeter |
Voltage (AC and dc) Current (AC and dc) Resistance Diode testing |
|
|
Function of selector switch on a digital multimeter. |
Allows choosing of quantity and range to be measured by connecting to specific ports on the circuit board |
|
|
What category meter would be used when measuring up to 480 volts. |
Category 3 voltmeter. |
|
|
Implications of incorrect connection to a circuit for an ammeter (in parallel) |
Draws excess current and due to low resistance burns out circuits. |
|
|
Implications for incorrect polarity connection for a voltmeter and ammeter |
The current simply runs in reverse, so readings on the meters will simply be negative. |
|
|
Possible implications if "prove test prove" tests arent done. |
Readings given could be incorrect due to calibration. |
|
|
Implications if an ohmmeter is connected to a live circuit. |
If connected in parallel the ammeter within the ohmmeter may be fried due to excess current. |
|
|
Megger use, quantity, and range |
Insulation resistance Resistance Mega ohms |
|
|
Why can't a multimeter be used in place of a megger. |
A multimeter can't stress the insulation with a high enough voltage like a dedicated ohmmeter. |
|
|
Electrical phenomena that a clip on ammeter uses. |
Electromagnetic induction. |
|
|
Type of meter you would use to test for continuity. |
Multimeter as ohmmeter or continuity tester. |
|
|
Why do certain instruments require magnetic shielding |
A measuring devices circuty is made up of a series of conductors and wires which are vulnerable to EM induction from other magnetic fields I.E the earth's. Magnetic shielding protects the internal circuitry in the instrument to keep measurements accurate. |
