17
T154 WS
TEMPERATURE DIAGNOSTICS
When one of the thermometers detects a temperature higher than 1 ° C with respect to the pre-set value as the alarm limit,
after approximately 5 seconds the
ALARM
relay switches and the channel
ALARM
LED (CH
n
)switches on.
When the trip temperature limit is exceeded, after approximately 5 seconds the
TRIP
relay switches and the channel
TRIP
LED (CH
n
) switches on.
As soon as the recorded temperature returns to values equal to or lower than the limit set for the
ALARM
and
TRIP
relays
switching, these relays de-energise and the corresponding LEDs switch off.
The values of
ALARM
and
TRIP
are kept in the internal memories: they can be recalled by entering the Vis modes (displaying
programmed parameters) and modifiable in the PRG mode (programming).
COOLING FAN CONTROL
The T154 WS control unit has a FAN contact (FAN1). If properly programmed, it can control the ON-OFF of the fans for
cooling of the transformer.
The contact of FAN1 is able to manage the cooling of the transformer or of the environment in which the cabin operates.
The fans can be controlled in two different ways:
•
Using the temperatures sensed by the sensors on the three columns
CHF
1.2.3
(e.g. ON at 70°C - OFF at 60°C)
•
Through an additional probe (
CH4/YES
) dedicated to the ambient temperature inside the transformer room
CHF
4
(e.g. ON at 45°C - OFF at 35°C)
The ON and OFF values are programmable according to the device range. The FAN ON must always be at least 1°C
higher than FAN OFF (recommended Δ FAN = 10°C).
The FAN 1 LED comes on when the temperature exceeds the FAN ON threshold by 1°C. The relative relay switches, and
turns off when the temperature goes below 1°C of the FAN OFF threshold. The relative relay switches go off when the
temperature goes below 1°C of the FAN OFF threshold and the relative relay switches.
FAN TEST
It is possible, by programming (
HFn
), to make sure that the fans are operated for 5 minutes every
xxx
” hours, regardless of
the temperature values of the columns or the environment (e.g.: with HFn = 001 the fans are activated for 5 minutes every
hour).
This function is designed to periodically check the operation of the fans and of their control equipment.
Setting
NO
, this function is inhibited.
To enable the HFN function, read the programming section on pages 13-14.
IMPORTANT INFORMATION
Before carrying out the isolation test of the electrical panel the control unit is installed on, disconnect it together
with the sensors from the power supply to prevent it from being seriously damaged.
