Data sheet, 4lsl – Procom 4LSL User Manual

Page 5

Data Sheet

4LSL

Loudspeaker Function Card

Short Circuit and Wire-Break Recognition

In loudspeaker circuits wire breaks and short circuits occur that are caused
by external effects and which lead to the outage of the loudspeakers. Short cir-
cuits or wire breaks are detected and signalled by the 4LSL module during each
subsequent measurement of the loudspeaker circuit.
When the service technician does the commissioning of the measuring module,
the function “Loudspeaker Circuit Safety Switch-off” [LK- Sicherheitsab-
schaltung

] can be activated. If a short circuit has been detected then it results

in a safety switch-off of the loudspeaker circuit. It switches off the loudspeaker
circuit that has the short circuit and prevents it from being turned on again. The
safety switch-off is only withdrawn after a subsequent measurement is made
without a short circuit in the loudspeaker circuit.

Generation of a Public Address Acknowledgement

When public address announcements are made to remote locations it cannot be
checked in person whether the announcement functioned properly or not. For
this the 4LSL measuring module generates a positive acknowledgement when a
public address announcement functioned properly.

To do this the 4LSL measures the power output (current and voltage) on the
loudspeaker circuit and compares it with configurable reference values.
Sufficiently high power consumption and the associated acoustic pressure re-
sults in a positive “public address acknowledgement”.

A positive public address acknowledgement is only given when a loud-
speaker circuit has a minimum amount of capability to make a public ad-
dress.

To check this the LED on the front plate can be switched to display mode “VU
Meter

”. Here the precise measurement level is displayed for each public ad-

dress measurement and each impedance measurement. Each channel (set)
can be switched over.

If a negative public address acknowledgement is additionally desired then this
can also be generated by the 4LSL measuring module.

Earth Leakage Message

If earth leakage is detected on the TG01 (audio signal generator) then this is al-
located unambiguously to a loudspeaker circuit by the 4LSL measuring module,
the message “Earth Leakage” [Erdschluss] is displayed and the passed on to
the DVS-21 system.

Date:

13.03.2009 Page:

5/7 Author:

Document-No.:

DB_4LSL_2830_01