Control Power; Contact Inputs - GE 845 Instruction Manual

ELECTRICAL INSTALLATION

Control Power

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Contact Inputs

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Control power is supplied to the relay such that it matches the relay's installed power
supply range.
Control power supplied to the relay must match the installed power supply range. If the
applied voltage does not match, damage to the unit may occur. All grounds MUST be
connected for normal operation regardless of control power supply type.
For more details, please refer to the Power Supply subsection located in the Introduction
chapter.
The relay should be connected directly to the ground bus, using the shortest practical
path. A tinned copper, braided, shielding and bonding cable should be used. As a
minimum, 96 strands of number 34 AWG should be used. Belden catalog number 8660
is suitable.
Figure 2-27: Control Power Connection
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.
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 2: INSTALLATION