đŸ”Ŧ DC Measuring Instruments

Session 2: Electrical Measurements

📊

Ammeter

Measures Electric Current (Amperes)

🔌 Connection Method

Series Connection

Must be connected in series with the circuit. Current flows through the ammeter.

📏 Typical Range

0.1 mA to 10 A

Different ranges available depending on application.

âš ī¸ Safety Caution

Never connect an ammeter in parallel! It can damage the meter or circuit due to low internal resistance.

🚗 Applications in Electric Vehicles

1
Measuring battery discharge current in EVs
2
Monitoring motor current draw
3
Testing charging current
4
Circuit troubleshooting and diagnostics
⚡

Voltmeter

Measures Voltage / Potential Difference (Volts)

🔌 Connection Method

Parallel Connection

Connected across the component to measure voltage difference.

📏 Typical Range

0.1 V to 1000 V

High voltage meters available for EV applications.

âš ī¸ Safety Caution

Always check voltage rating before measurement to avoid meter damage. Use appropriate range setting.

🚗 Applications in Electric Vehicles

1
Measuring battery pack voltage
2
Checking individual cell voltages in battery packs
3
Testing charging system voltage
4
Voltage drop measurements across components
đŸŽšī¸

Ohmmeter

Measures Electrical Resistance (Ohms Ί)

🔌 Connection Method

Parallel Connection

Circuit must be de-energized (power off) before measurement.

📏 Typical Range

0.1 Ί to 100 MΊ

Wide range for different component testing.

âš ī¸ Safety Caution

Always disconnect power before measuring resistance! Measuring resistance in a powered circuit damages the meter.

🚗 Applications in Electric Vehicles

1
Testing motor winding resistance
2
Checking cable continuity and integrity
3
Measuring sensor resistance values
4
Detecting short circuits and open circuits
🔧

Multimeter

Measures Voltage, Current, Resistance, & More

🔌 Connection Method

Varies by Mode

Series for current, parallel for voltage/resistance. Always select correct mode first!

📏 Typical Range

Multiple ranges for all parameters

Auto-ranging available on digital models.

âš ī¸ Safety Caution

Select correct mode before connecting! Wrong mode selection can damage the meter or cause safety hazards.

🚗 Applications in Electric Vehicles

1
All-in-one diagnostic tool for EV systems
2
Battery management system testing
3
Power electronics troubleshooting
4
General electrical diagnostics and maintenance

Quick Reference Comparison

Instrument Measures Connection Symbol
Ammeter Current (Amperes) Series A
Voltmeter Voltage (Volts) Parallel V
Ohmmeter Resistance (Ohms) Parallel (power off) Ί
Multimeter All of the above Varies by mode VΊA
Next →