Sink

What Is a Sink?

In electrical engineering, a sink is any component, circuit, or instrument that absorbs electrical energy and converts it into heat, light, or mechanical power. A sink is the functional counterpart to a source, which provides voltage and power. In test and measurement, the term is especially important because many test setups rely on a defined power draw.

Key Characteristics of a Sink

Energy Absorption / Current Sink: A sink draws current from a circuit. While the source performs sourcing, the sink provides the current path to 0 V/ground or the negative terminal.
Typical Examples: Resistors, incandescent lamps, heating elements, motors, and especially electronic loads as defined current sinks for power supply testing, battery testing, DC/DC and AC/DC testing, and load simulation.
Sinking Logic in Automation: In PLC and control engineering, sinking refers to inputs that complete the current flow to ground (0 V) (counterpart: sourcing).
Field Theory / Polarity: In simplified representations, the negative terminal is considered the sink where field lines terminate, while the positive terminal is considered the source.

Passive Sink vs. Active Sink

Passive Sinks: e.g., resistors with fixed power dissipation.
Active Sinks: e.g., programmable electronic DC loads that precisely regulate current, voltage, resistance, or power (CC, CV, CR, CP) and generate dynamic load profiles.

Example of a Sink: Electronic DC Load in Test and Measurement

An electronic DC load is a professional, controllable current sink for repeatable testing, including transients, short-circuit simulation, protection tests (OVP, OCP, OPP, OTP), and high-precision voltage and current measurement.