Flexelements - GE MI-869 Instruction Manual

FLEXLOGIC

FlexElements

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There are 8 identical FlexElements™. A FlexElement is a universal comparator, that can be
used to monitor any analog actual value measured or calculated by the relay, or a net
difference of any two analog actual values of the same type. Depending on how the
FlexElement is programmed, the effective operating signal could be either a signed signal
("Signed" selected for Input Mode), or an absolute value ("Absolute" selected for Input
Mode).
The element can be programmed to respond either to a signal level or to a rate-of-change
(delta) over a pre-defined period of time. The output operand is asserted when the
operating signal is higher than a threshold or lower than a threshold as chosen by the user.
When programming a FlexElement, one must keep in mind the following limitations:
1. The analog inputs for any FlexElement must be from the same "gender":
– current and current (in any combination, phase-symmetrical, phase-phase, kA-A,
differential, restraint, etc.)
– voltage and voltage (as above)
– active power and active power (Watts and Watts)
– reactive power and reactive power (Vars and Vars)
– apparent power and apparent power (VA and VA)
– angle and angle (any, no matter what signal, for example angle of voltage and
angle of current are a valid pair)
– % and % (any, for example THD and harmonic content is a valid pair)
– V/Hz and V/Hz
– °C and °C
2 2
– I t and I t
– FlexElement actual and FlexElement actual
For all the other combinations, the element displays 0.000 or N/A and will not assert
any output operand.
2. The analog value associated with one FlexElement can be used as an input to another
FlexElement "Cascading".
Figure 4-146: FlexElement logic diagram
869 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 4: SETPOINTS