GE t60 Instruction Manual page 69

3 HARDWARE
I
V
a) Voltage with optional
Voltage monitoring only
current monitoring
V
I
b) Current with optional
Current monitoring only
voltage monitoring
c) No monitoring
Figure 3–16: FORM-A AND SOLID-STATE CONTACT OUTPUTS WITH VOLTAGE AND CURRENT MONITORING
The operation of voltage and current monitors is reflected with the corresponding FlexLogic™ operands (
, and
CONT OP # VOFF CONT OP # ION
the voltage monitor is breaker trip circuit integrity monitoring; a typical application of the current monitor is seal-in of the
control command.
Refer to the Digital elements section of chapter 5 for an example of how form-A and solid-state relay contacts can be
applied for breaker trip circuit integrity monitoring.
Relay contacts must be considered unsafe to touch when the unit is energized! If the relay contacts need to
be used for low voltage accessible applications, it is the customer's responsibility to ensure proper insula-
WARNING
tion levels!
USE OF FORM-A AND SOLID-STATE RELAY OUTPUTS IN HIGH IMPEDANCE CIRCUITS
For form-A and solid-state relay output contacts internally equipped with a voltage measuring cIrcuit across the
NOTE
contact, the circuit has an impedance that can cause a problem when used in conjunction with external high input
impedance monitoring equipment such as modern relay test set trigger circuits. These monitoring circuits may con-
tinue to read the form-A contact as being closed after it has closed and subsequently opened, when measured as
an impedance.
The solution to this problem is to use the voltage measuring trigger input of the relay test set, and connect the form-
A contact through a voltage-dropping resistor to a DC voltage source. If the 48 V DC output of the power supply is
used as a source, a 500 Ω, 10 W resistor is appropriate. In this configuration, the voltage across either the form-A
contact or the resistor can be used to monitor the state of the output.
Wherever a tilde "~" symbol appears, substitute with the slot position of the module; wherever a number
sign "#" appears, substitute the contact number
NOTE
When current monitoring is used to seal-in the form-A and solid-state relay contact outputs, the Flex-
Logic™ operand driving the contact output should be given a reset delay of 10 ms to prevent damage of
NOTE
the output contact (in situations when the element initiating the contact output is bouncing, at values in the
region of the pickup value).
GE Multilin
~#a
If Idc 1mA, Cont Op 1 = "VOn"
~#b
otherwise Cont Op 1 = "VOff"
Load
~#c
~#a
If Idc 80mA, Cont Op 1 = "IOn"
~#b
otherwise Cont Op 1 = "IOff"
Load
~#c
~#a
~#b
Load
~#c
) which can be used in protection, control, and alarm logic. The typical application of
T60 Transformer Protection System
~#a
I
~#b
V
~#c
+
Both voltage and current monitoring
~#a
V
I ~#b
~#c
+
Both voltage and current monitoring
(external jumper a-b is required)
+
3.2 WIRING
If Idc 80mA, Cont Op 1 = "IOn"
otherwise Cont Op 1 = "IOff"
If Idc 1mA, Cont Op 1 = "VOn"
otherwise Cont Op 1 = "VOff"
Load
+
If Idc 80mA, Cont Op 1 = "IOn"
otherwise Cont Op 1 = "IOff"
If Idc 1mA, Cont Op 1 = "VOn"
otherwise Cont Op 1 = "VOff"
Load
+
827862A3.CDR
,
CONT OP # VON
3-15
3