Which component must the isolator be placed in series with for testing?

The isolator must be placed in series with the power supply and the ammeter for testing because this configuration allows for accurate measurement of the current flowing through the system. When testing electrical circuits, it is essential to measure current while ensuring that the circuit can be safely isolated from other components to avoid potential damage or inaccuracies.

By placing the isolator in series with both the power supply and the ammeter, you create a straightforward pathway for current to flow. This setup allows for the ammeter to accurately capture the current reading and provides the necessary isolation to avoid disturbances caused by other components within the system.

Other components like voltage regulators or capacitor banks are typically used to manage voltage or store energy but do not serve the specific purpose of measuring current in an isolated manner. Transformers, while important in electrical systems, would require a different testing methodology that does not involve the same series connection with an ammeter for current measurements. Thus, placing the isolator in series with the power supply and ammeter enables precise testing while isolating the measuring instruments from the influence of other circuit elements.