Contact Inputs; Output Relays - GE 845 Instruction Manual

ELECTRICAL INSTALLATION

Contact Inputs

FASTPATH:
INPUT
SIGNAL
SWITCH
(WET)
EXTERNAL
DC POWER
SUPPLY

Output Relays

2–20
Depending on the order code, the 845 relay has a different number of contact inputs which
can be used to operate a variety of logic functions for circuit switching device control,
external trips, blocking of protection elements, etc. The relay has 'contact inputs' and
'virtual inputs' that are combined in a form of programmable logic to facilitate the
implementation of various schemes.
The voltage threshold at which the contact inputs detect a closed contact input is
programmable as 17 V DC for 24 V sources, 33 V DC for 48 V sources, 84 V DC for 110 to
125 V sources, and 166 V DC for 250 V sources.
Wet or Dry input signal types can be connected to contact input terminals as shown in the
figure: Wet and Dry Contact Input Wiring Examples.
Dry inputs use an internal +24V that is supplied by the 845. The voltage threshold must be
set to 17V for the inputs to be recognized using the internal +24V.
The same type of input signal must be connected to all contact inputs on the same contact
input card.
Figure 2-24: Wet and Dry Contact Input Wiring Examples
The output relays for the 845 relay are fully programmable, and can be assigned in the
transformer breakers menu for breaker tripping or closing. The output relays assigned for
breaker closing, are automatically excluded from the menus for output selection for the
rest of the elements.
The critical output relay is reserved as Relay_8 and it is omitted and is not programmable.
INPUT
SIGNAL
SWITCH
(DRY)
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 2: INSTALLATION