What is the only way to check the operation of a solid state relay?

The solid state relay (SSR) is a type of relay that uses semiconductor devices to perform the switching operation, thereby eliminating the need for mechanical movement. To check the operation of a solid state relay effectively, an ammeter is often used because it allows for the measurement of current flowing through the relay. This current measurement is critical since the primary function of a SSR is to switch electrical loads on and off, and the ammeter can verify that the relay is passing the required load current when activated.

While devices like oscilloscopes and multimeters can provide useful information about the electrical characteristics of the relay, they do not directly provide an indication of the relay's ability to conduct current under load conditions during its operational state. Specifically, oscilloscopes are better suited for observing waveform characteristics and not for measuring current directly. Conversely, a digital multimeter can measure voltage and continuity but isn’t as effective for assessing the performance of a solid state relay under load conditions like an ammeter can.

Using an ammeter to check the operation ensures that you confirm not only the functioning of the SSR but also its capability to handle the specified electrical loads, making it the most appropriate tool for this purpose.