GE L90

CHAPTER 5: SETTINGS INPUTS/OUTPUTS
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL 5-419
5
Since the two physical contacts in this example are mechanically separated and have individual control inputs, they do not
operate at exactly the same time. A discrepancy in the range of a fraction of a maximum operating time can occur.
Therefore, a pair of contacts programmed to be a multi-contact relay do not guarantee any specific sequence of operation
(such as make before break). If required, the sequence of operation must be programmed explicitly by delaying some of the
control inputs as shown in the next application example.
Application example 3
A make before break functionality must be added to the preceding example. An overlap of 20 ms is required to implement
this functionality.
Write the following FlexLogic equation (EnerVista example shown).
Set both timers (Timer 1 and Timer 2) to 20 ms pickup and 0 ms dropout.
Program the Latching Outputs by making the following changes in the
SETTINGS  INPUTS/OUTPUTS  CONTACT
OUTPUTS  CONTACT OUTPUT H1a
and CONTACT OUTPUT H1c menus (assuming an H4L module):
OUTPUT H1a OPERATE: “VO1”
OUTPUT H1a RESET: “VO4”
OUTPUT H1c OPERATE: “VO2”
OUTPUT H1c RESET: “VO3”
Application example 4
A latching contact H1a is to be controlled from a single virtual output VO1. The contact is to remain closed as long as VO1
is high, and is to remain opened when VO1 is low. Program the relay as follows.
Write the following FlexLogic equation (EnerVista example shown).
Program the Latching Outputs by making the following changes in the
SETTINGS  INPUTS/OUTPUTS  CONTACT
OUTPUTS  CONTACT OUTPUT H1a
menu (assuming an H4L module):
OUTPUT H1a OPERATE: “VO1”
OUTPUT H1a RESET: “VO2”