Testing intrinsic-safety barriers with an electronic load & DMM

Intrinsic safety (IS) protects equipment in hazardous areas by limiting the electrical and thermal energy available for ignition. IS designs use special fusing and dissipating elements that must never exceed their temperature rating — even during a fault. Verifying that is a power-and-temperature test, and an electronic load makes it repeatable.

The test in one sentence

Load the circuit to its maximum rated power, wait the specified soak time, and measure the temperature of every element that dissipates — heatsinks, packages, resistors, traces. A power-resistor network works, but an SDL1000X electronic load (200/300 W) is far more convenient: Constant Power mode holds the exact wattage regardless of voltage drift, with CR/CV modes and user-defined limits for safe operation.

Step by step

• Connect the device under test to the load's input terminals
• Select Constant Power (CP) mode
• Set the current and voltage ranges (I_range / V_range) for the test
• Set the power the load should sink and activate the input
• After the soak time required by your standard, measure component temperatures

Multi-point temperature logging

Use a thermal camera for a quick overview, or thermocouples with a bench multimeter for documented numbers. The SDM3055-SC and SDM3065X-SC scanner-card multimeters monitor up to 12 thermocouples simultaneously — heatsink, fuse, barrier resistors and PCB hot spots in one logged sweep.