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CHAPTER 2: USING THE RTT ON SR SERIES RELAYS
THE SR745 TRANSFORMER MANAGEMENT RELAY
RTT DESKTOP TEST SET– INSTRUCTION MANUAL
35
2.4
The SR745 Transformer Management Relay
2.4.1
Overview
The SR745 Relay has three groups of 3-phase current inputs with CT burden less than
0.2 VA at rated load and has one voltage input with VT burden less than 0.025 VA at rated
120 V. External contacts can be connected to the relay’s 16 logic inputs. These contacts
can be either Dry or Wet (which requires an external source voltage greater than 30 VDC).
The SR745 Relay is equipped with 8 output relays. The SR745 Relay provides one 3-wire
RTD input which can be field programmable as a 3-wire type of 100 Platinum, 100 Nickel
and 120 Nickel.
All features of RTT can be applied to the SR745 Relay, but only one RTD is used. No
modification to the Test Cable is required.
Unused Wires
For the unused wires (6 in total), it is recommended that user tape the lugs to ensure
isolation of the contacts and so that no problems are caused by wires touching.
The unused wires are: R2+, R2-, R2C, R3+, R3- and R3C.