GE C70, Instruction Manual

Page: 70 / 708

3-12 C70 Capacitor Bank Protection and Control System GE Multilin
3.2 WIRING 3 HARDWARE
3
3.2.5 PROCESS BUS MODULES
The C70 can be ordered with a process bus interface module. This module is designed to interface with the GE Multilin
HardFiber system, allowing bidirectional IEC 61850 fiber optic communications with up to eight HardFiber merging units,
known as Bricks. The HardFiber system has been designed to integrate seamlessly with the existing UR-series applica-
tions, including protection functions, FlexLogic, metering, and communications.
The IEC 61850 process bus system offers the following benefits:
• Reduces labor associated with design, installation, and testing of protection and control applications using the C70 by
reducing the number of individual copper terminations
• Integrates seamlessly with existing C70 applications, since the IEC 61850 process bus interface module replaces the
traditional CT/VT modules
• Communicates using open standard IEC 61850 messaging
For additional details on the HardFiber system, see GE publication GEK-113658: HardFiber Process Bus System Instruc-
tion Manual.
3.2.6 CONTACT INPUTS AND OUTPUTS
Every contact input/output module has 24 terminal connections. They are arranged as three terminals per row, with eight
rows in total. A given row of three terminals can be used for the outputs of one relay. For example, for form-C relay outputs,
the terminals connect to the normally open (NO), normally closed (NC), and common contacts of the relay. For a form-A
output, there are options of using current or voltage detection for feature supervision, depending on the module ordered.
The terminal configuration for contact inputs is different for the two applications.
The contact inputs are grouped with a common return. The input/output modules have two versions of grouping: four inputs
per common return and two inputs per common return. When a contact input/output module is ordered, four inputs per com-
mon is used. If the inputs must be isolated per row, then two inputs per common return should be selected (4D module).
The tables and diagrams on the following pages illustrate the module types (6A, etc.) and contact arrangements that can be
ordered for the relay. Since an entire row is used for a single contact output, the name is assigned using the module slot
position and row number. However, since there are two contact inputs per row, these names are assigned by module slot
position, row number, and column position.
Some form-A / solid-state relay outputs include circuits to monitor the DC voltage across the output contact when it is open,
and the DC current through the output contact when it is closed. Each of the monitors contains a level detector whose out-
put is set to logic “On” when the current in the circuit is above the threshold setting. The voltage monitor is set to “On” when
there is a voltage across open contact (the detector allows a current of about 1 to 2.5 mA), and the current monitor is set to
“On” when the current flowing through the closed contact exceeds about 80 to 100 mA. The voltage monitor is intended to
check the health of the overall trip circuit, and the current monitor can be used to seal-in the output contact until an external
contact has interrupted current flow. If enabled, the current monitoring can be used as a seal-in signal to ensure that the
form-A contact does not attempt to break the energized inductive coil circuit and weld the output contacts.
Block diagrams are shown as follows for form-A and solid-state relay outputs with optional voltage monitor, optional current
monitor, and with no monitoring. The actual values shown for contact output 1 are the same for all contact outputs. Form-A
contact output with or without a current or voltage monitoring option is not polarity sensitive. The polarity shown in the figure
is required for solid-state contact output connection.