Understanding DC Amp Meters
* Purpose: DC amp meters measure the flow of electrical current (amperes) in a direct current (DC) circuit.
* Types:
* Analog: Use a needle that moves across a calibrated scale.
* Digital: Display the current reading numerically.
* Connections: Most DC amp meters have two terminals:
* Positive (+) Terminal: Connected to the positive side of the circuit.
* Negative (-) Terminal: Connected to the negative side of the circuit.
Hooking Up a DC Amp Meter
1. Safety First:
* Power Off: Always disconnect the circuit from the power source before working on it.
* Use Appropriate Tools: Use insulated tools to avoid electrical shock.
* Know the Circuit: Identify the positive and negative leads in your circuit.
2. Circuit Interruption:
* Series Connection: DC amp meters must be placed in series with the component or section of the circuit you want to measure. This means you need to break the circuit and insert the meter into the break.
3. Connections:
* Positive (Red) Terminal: Connect the positive terminal of the amp meter to the wire leading to the positive side of the circuit.
* Negative (Black) Terminal: Connect the negative terminal of the amp meter to the wire leading to the negative side of the circuit.
* Secure Connections: Make sure the connections are tight and secure to prevent loose connections.
4. Power On: Turn the power back on to the circuit.
5. Reading the Meter:
* Analog: Observe the needle position on the calibrated scale.
* Digital: Read the numerical value displayed on the meter.
Important Notes:
* Meter Range: Choose an amp meter with a range that accommodates the expected current flow in your circuit. A meter with too small a range can be damaged.
* Polarity: Connect the meter terminals to the correct polarity in the circuit. Reversing the connections can damage the meter and/or circuit.
* Measuring Large Currents: For very high currents, you may need to use a shunt resistor in conjunction with a lower-range amp meter.
Example: Measuring Current in a DC Motor
1. Disconnect the motor from the power supply.
2. Cut one of the motor's power wires.
3. Connect the positive terminal of the amp meter to the cut wire.
4. Connect the negative terminal of the amp meter to the other end of the cut wire.
5. Reconnect the motor to the power supply.
6. Observe the current reading on the amp meter.
Remember:
* Always practice proper safety precautions when working with electricity. If you're unsure about any aspect of the process, consult an experienced electrician.
* Never work on live circuits.