POWER SUPPLY
The T154 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 bars of the transformer secondary and there is a fixed bank of capacitors to
correct the power factor of the transformer itself.
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.
ALARMS AND VENTILATION
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.
Relay test.
The ALARM and TRIP relays switch only when the set temperature thresholds are exceeded.
The FAULT relay switches when the unit is powered on and holds till one of the following events takes place:
Data storage fault (Ech message).
Failure of the Pt100, Ni100 or Ni120 sensors (FCC short-circuited sensor, FOC open sensor or Fcd
quick temperature increase).
CAL damage to the measurement circuit.
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.
The FAN contact can be used to control the cooling fans or it can be inserted into the air conditioning system of the room
where the transformer is located.
NOTE: always disconnect the unit before performing any electrical connections.
THERMOMETRIC SENSOR CONNECTION
Each Pt100 (Ni100 or Ni120 optional) thermometric sensor has one white and two red connectors (IEC 75.8
regulations). The CH2 channel must be always referred to the central column of the transformer.
The CH4 channel must be always referred either to the core of the transformer or to the Pt100 ambient sensor if you
wish to thermo-regulate the transformer room using the T154 control unit.
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