CESVA RS-60 Manual Del Usuario página 24

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The following figure represents the REL-2 relay box. As you can see, each of the two relays
has 3 contacts.
When the sound pressure level is correct (below the corresponding limit), the relay connects
terminals 1 and 2. When the corresponding limit is exceeded, the relay switches and
connects terminals 2 and 3. This makes it possible both to activate and deactivate electrical
signals no higher than 220 V / 1 A.
If you want to activate an electrical signal when the sound pressure level exceeds a certain
level (for example, if you want to light a bulb), the signal must be connected to terminals 1
and 2 of the relay. In this way, when the sound pressure level is correct, the bulb will remain
off and when the programmed limit is exceeded it will come on. If, on the other hand, you
want to deactivate a signal when the sound pressure level exceeds the programmed limit (for
example, if you want to disconnect a hi-fi set), the set must be connected to terminals 2 and
3 of the relay. Thus, while the sound pressure level is correct the set will work, but once the
programmed limit is exceeded the relay will switch and the set will cease to work.
The following diagram shows how the pre-alarm and alarm relays work depending on the
pre-alarm and alarm limits, on the average sound pressure level and on switching time. In
example A, a pre-alarm limit of 85 dB, an alarm limit of 90 dB and pre-alarm and alarm
switching times of 4 and 5 seconds respectively. In example B, the same limits have been
maintained, but the pre-alarm switching time has been programmed at 1 second and the
alarm switching time at 2 seconds. The evaluation time is 3 seconds in both examples.
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