GE M60 Instruction Manual page 56

WIRING
Figure 3-13: Form-A and solid-state contact outputs with voltage and current monitoring
3
The operation of voltage and current monitors is reflected with the corresponding FlexLogic operands (
, and
# VOFF CONT OP # ION
monitor is breaker trip circuit integrity monitoring; a typical application of the current monitor is seal-in of the control
command.
See 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.
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
NOTE
the 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 can continue to read the form-A contact as being closed after it has closed and subsequently opened,
when measured as an impedance.
The solution 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.
Where a tilde "~" symbol appears, substitute the slot position of the module. Where a number sign "#" appears,
substitute the contact number.
NOTE
3-14
) that can be used in protection, control, and alarm logic. The typical application of the voltage
Consider relay contacts unsafe to touch when the unit is energized.
CHAPTER 3: INSTALLATION
M60 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
,
CONT OP # VON CONT OP