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16
FO 935
Output relays with 10A-250Vca-
res COSФ=1 contacts
RELAY CONNECTION EXAMPLE
1MN0095 REV.0
ATTENTION: Before carrying out any electrical test on the transformer or on the panel, e.g. dielectric
strength etc., it is advisable to disconnect all the components of the FO system. Any noise or
voltage peaks on the inputs or on the power supply could cause the failure of: sensors, concentrator
or control unit.
POWER SUPPLY
The FO 935 control unit can be supplied by 85 to 260 Vdc-Vac, 50/60 Hz irrespectively of polarity in Vdc (terminals 40 - 42).
This particularity is obtained thanks to the use of a tested power supply, of new conception and realisation,
which frees the installer from any uncertainty regarding the correct Vac or Vdc power supply.
The earthing cable must always be connected to terminal 41.
When the control unit is powered directly by the secondary of the transformer to be protected, it can be burnt out by high
intensity overvoltages.
These problems occur if the main switch is closed and the transformer does not have the load (no load test).
The above is much more evident when the 220 Vac voltage is taken directly from the bars of the secondary
of the transformer and there is a fixed capacitor battery for power factor correction of the transformer itself.
To protect the control unit against line overvoltages, the PT-73-220 electronic arrester,designed by TECSYSTEM S.r.l. for
this specific purpose, is recommended. Alternatively, it is advisable to use power supply voltages 110 Vac or, even better,
110 Vdc.
If an existing control unit must be replaced with a new one, to guarantee its correct and safe operation, the
sensor/relay/supply connecting terminals must be replaced with the new terminals supplied.
AUDIBLE AND VISUAL
INDICATION
ALARM CONDITION
SYSTEM
SHUTDO
WN
Note: image relay contacts in non-alarm condition, except for the FAULT relay which switches: contacts 10
–11
closed (NO) contacts 9-11 open (NO) fault condition identification. Read paragraph Alarms and Ventilation p. 17 and
see image of fault contact switching.