Exclusive Canadian Distributor
EL Switchgear & Control Inc
Ph: 1 800 463 1275 Fax1 519 753 5755
February 19,2007
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Inputs The T154 will accept three or four, three-wire RTD inputs.
The standard unit is calibrated for 100-ohm, platinum RTDs.
The T154 may also be ordered for use with 100 or120-ohm, nickelRTDs.
Channels 1-2-3 must have inputs connected or the unit will read an open
circuit with the FOC message displayed, and the fault relay tripped. In
applications with less than three channels connected, a resistor of 100 ohms or
more must be connected across the open channel. This will eliminate nuisance
tripping of the fault relay. The display will show a value for the unused
channel, which is based on resistance vs.temperature for 100 ohm platinum
RTD’s. To select a resistance value corresponding to a temperature value, a
100 ohm resistor is equivalent to 0°C. Each 3.89 ohms (minus .01 per
increment) is equivalent to 10°C. Ensure this does not interfere with the alarm
or trip set points. Always choose a fixed resistance to provide a value lower
than the set point values on the active channels.
Applications with transformers requires the RTD’s to be connected in
sequence for best performance, i.e. Winding 1-2-3 connected to channels 1-2-
3
Channel 4 is a programmable option. This channel may be enabled/disabled in
the program mode.
Outputs The standard version of the T154 incorporates four output relays.These are:
Trip, Alarm, Fault and Fan.
•Alarm , Trip & Fault relays are single-pole, double throw, fan relays are
SPST.
•The Alarm, and Trip relays may be programmed with individual
temperature set point values All channels will respond to the
programmed values.
•The Fan relay may be programmed with an ON and Off set point
temperature value. The operation is selected in program mode. Two
choices are offered; one based on RTD inputs connected to channels 1,2
or 3 or; controlled by an RTD connected to channel 4. The fan relay
incorporates a fan test procedure this is selected in program mode. This
feature allows automatic cycling of the fans five minutes of a selected
hourly interval from one to ninty nine hours. To disable this feature enter
ooo
•The alarm and trip relays will change contact state when the set-point
temperature value is reached. This value must be present for a minimum
of fourseconds in excess of 1 degree C above the set-point threshold
•The Fault relay is activated when the unit senses a defective component or
failure of the relay. This relay changes contact state when the unit is
powered on line. Resetting this relay requires repair, replacement or
correction of components. Resetting the fault relay is affected by the FCD
program selection, refer toSCREEN MESSAGES for more detail..
•Output relays are controlled by set-point thresholds for alarm trip and fan
relays. Each channel surveys the temperature independently, and the
hottest channel will cause the relays to trip when the threshold is
exceeded. The reset function requires all channels to drop one degree C
below the trip thresholds and the relays reset automatically.
