A method and test device for testing protection relays, the test device having a signal generator. The signal generator supplies a signal as pulses having pause times, which alternate over time. Signal level is reduced during the pause times and at least one pulse has an amplitude at least higher than one of the preceding pulses. A supply voltage is supplied by an accumulator providing electric energy for generating the pulses. Via the accumulator, a greater mobility and flexibility is ensured, and fuel-fed power units or emergency power units may be omitted. In order to reduce the load (average energy) on the accumulator, the signal generator emits the signal as pulses having pause times. The pulse amplitudes may have an increasing trend to reach a switching threshold. This allows the use of smaller and more compact, which is important for a portable test device.