4–290 845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
MONITORING CHAPTER 4: SETPOINTS
RTD Temperature
RTD Wiring Diagram
Figure 4-118: RTD Wiring diagram
NOTE:
To enhance the accuracy of the RTD, ensure all 3 cables are of the same length and gauge.
In addition, the Compensation and Return wires must be connected on the RTD side and
not on the relay side.
RTD Inputs
Hardware and software is provided to receive signals from external Resistance
Temperature Detectors (RTDs) and convert these signals into a digital format for use as
required. These channels are intended to be connected to any of the RTD types in common
use.
Depending on the order code (Advanced Monitoring option selected), the 845 relay is
packaged with one combo card consisting of one RTD input, one Ohms input, four DCmA
inputs and seven DCmA outputs. Additionally, the relay can be furnished with up to two
optional RTD cards, each of them having 6 RTD input channels. Only slots “B” and “C” can
accept the optional RTD cards.
NOTE:
If only one RTD card is ordered at the time the relay is ordered, this RTD card is always
shown in slot B. The order code selection does not allow for an RTD card in slot C, if no RTD
card is ordered in slot B.
NOTE:
An LVIO card ordered in Slot G will contain an additional RTD input on the card. It will be the
highest RTD number shown (i.e. if 1 additional RTD card is used, then the LVIO RTD will be
RTD #7).
An alphanumeric name is assigned to each channel; this name is included in the channel
actual values. It is also used to reference the channel as the input parameter to features
designed to measure this type of parameter. Selecting the type of RTD connected to the
channel configures the channel. The conversion chart is shown in the RTD Temperature vs.
Resistance table.
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