Contact Inputs/Outputs - GE L90 Instruction Manual

3.2 WIRING
Every digital input/output module has 24 terminal connections. They are arranged as 3 terminals per row, with 8 rows in
total. A given row of three terminals may 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 out-
put, 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. When a digital input/output module is ordered
with contact inputs, they are arranged in groups of four and use two rows of three terminals. Ideally, each input would be
totally isolated from any other input. However, this would require that every input have two dedicated terminals and limit the
available number of contacts based on the available number of terminals. So, although each input is individually optically
isolated, each group of four inputs uses a single common as a reasonable compromise. This allows each group of four out-
puts to be supplied by wet contacts from different voltage sources (if required) or a mix of wet and dry contacts.
The tables and diagrams on the following pages illustrate the module types (6A, etc.) and contact arrangements that may
3
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.
UR-SERIES FORM-A / SOLID STATE (SSR) OUTPUT CONTACTS:
Some Form-A/SSR 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 output is set to
logic "On = 1" when the current in the circuit is above the threshold setting. The voltage monitor is set to "On = 1" when the
current is above about 1 to 2.5 mA, and the current monitor is set to "On = 1" when the current 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. The block diagrams of the circuits are below
above for the Form-A outputs with:
a) optional voltage monitor
b) optional current monitor
c) with no monitoring
a) Voltage with optional
current monitoring
V
b) Current with optional
voltage monitoring
c) No monitoring
3-10
~#a
I
If Idc 1mA, Cont Op x Von
~
~#b
otherwise Cont Op x Voff
V
~#c
Voltage monitoring only
~#a
If Idc 80mA, Cont Op x Ion
~
~#b
otherwise Cont Op x Ioff
I
~#c
Current monitoring only
~#a
~#b
~#c
Figure 3–12: FORM-A /SOLID STATE CONTACT FUNCTIONS
L90 Line Differential Relay

3.2.5 CONTACT INPUTS/OUTPUTS

I
-
Load V
+
Both voltage and current monitoring
V
-
I
Load
+
Both voltage and current monitoring
(external jumper a-b is required)
-
Load
+
3 HARDWARE
If Idc 80mA, Cont Op x Ion
~
otherwise Cont Op x Ioff
~#a
If Idc 1mA, Cont Op x Von
~
otherwise Cont Op x Voff
~#b Load
~#c
If Idc 80mA, Cont Op x Ion
~
otherwise Cont Op x Ioff
~#a
If Idc 1mA, Cont Op x Von
~
otherwise Cont Op x Voff
~#b
Load
~#c
827821A5.CDR
GE Multilin
-
+
-
+