Measurement-computing PCM-DAS08 Uživatelský manuál stáhnout pdf (Strana 9)

3.3 GROUND LOOP EXAMPLE

Figure 3-3 shows a single-ended

analog input connected incorrectly. The resulting

ground loop may introduce an error to the input signal.

Figure 3-3. Incorrect Connections Causing a Ground Loop

3.4 BEWARE OF VOLTAGE SPIKES

Although your Laptop may not be grounded, that does not mean that you can connect

the PCM-DAS08 to a signal that is subject to voltage spikes. Even though the Laptop

has no reference to ground, it has more capacitive mass than the PCM-DAS08 inputs

can bear. If the signal you are measuring suddenly swings greater than +/-15V, the

weak link in the circuit will fail. That weak link is your PCM-DAS08 analog input

circuit.

This is true of any A/D board not protected by isolation amplifiers

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Measurement-computing PCM-DAS08 Uživatelský manuál Strana 9