10
T412 SERIES
POWER SUPPLY
The T412 control unit has UNIVERSAL power supply, i.e. it can be supplied by 24 to 240 Vac-Vdc, 50/60 Hz irrespectively of
polarity in Vdc (terminals 40-42).
This is obtained thanks to the use of a tested power supply unit, newly designed and manufactured, that frees installers from
worrying about the correct Vac and Vdc supply.
Earth must always be connected to terminal 41.
When the unit is supplied directly by the secondary of the transformer to be protected, it can be burnt out by strong
overvoltages.This happens if the main switch is closed and the transformer has no load (blank test). The above is much
more obvious when the voltage of 220 Vac is taken directly from the secondary bars
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.
ALARM ELECTRICAL CONNECTIONS
Carry out the electrical connections on the removable terminal blocks only after disconnecting them from the unit.
When the control unit is in one of the modes mentioned below, it does not monitor the temperature and the relays are all
blocked.
Vis. programming display
PRG Programming.
The L1 and L2 relays switch only when the ALL1 and ALL2 set temperature thresholds are exceeded.
The FAULT relay switches when the unit is powered and holds till one of the following events takes place:
Pt100 sensor fault (FCC short-circuited sensor, FOC interrupted sensor or Fcd quick temperature increase)
TCK sensor fault (FOC interrupted sensor)
Insufficient supply voltage.
During the power on reset after programming (PRG) the control unit.
NOTE: do not connect the FAULT relay to the transformer tripping circuit to avoid unwanted system interruptions.
Note: with the power to the unit ON, FAULT relay switches, contacts 8-9 open (NO) 7-9 closed (NC).
FAULT 8-9 NC: ALARM FAULT OR POWER OFF
FAULT 7-9: NC POWER ON
NOTE: always disconnect the unit power supply performing any electrical connection
ATTENTION:
We recommend you check the control unit before starting the device.
The default parameters set by TECSYSTEM might not suit your requirements.
Programming the device is the end user’s responsibility: the set alarm thresholds and the enabled functions
described in this manual must be checked (by a specialized technician) referring them to the application and
system characteristics on which the control unit is installed.
PROGRAMMING
To protect the control unit from line overvoltages, we recommend using the electronic PT-73-220 surge limiter,
designed by TECSYSTEM S.r.l. specifically for this purpose.
Alternatively we recommend you adopt 24 Vac or, even better, 24 Vdc supply voltages.
