5-236 T35 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
CONTROL ELEMENTS CHAPTER 5: SETTINGS
5
Example 2: Breaker trip circuit integrity monitoring
If it is required to monitor the trip circuit continuously, independent of the breaker position (open or closed), a method to
maintain the monitoring current flow through the trip circuit when the breaker is open must be provided (as shown in the
following figure). This can be achieved by connecting a suitable resistor (see figure) across the auxiliary contact in the trip
circuit. In this case, it is not required to supervise the monitoring circuit with the breaker position – the
BLOCK setting is
selected to “Off.” In this case, the settings are as follows (EnerVista example shown).
Figure 5-124: Trip circuit example 2
5.8.6 Underfrequency (ANSI 81U)
SETTINGS CONTROL ELEMENTS UNDERFREQUENCY UNDERFREQUENCY 1(6)
The wiring connection for two examples above is applicable to both form-A contacts with voltage monitoring and
solid-state contact with voltage monitoring.
UNDERFREQUENCY 1
UNDFREQ 1 FUNCTION:
Disabled
Range: Disabled, Enabled
UNDERFREQ 1 BLOCK:
Off
Range: FlexLogic operand
UNDERFREQ 1 SOURCE:
SRC 1
Range: SRC 1, SRC 2, SRC 3, SRC 4, SRC 5, SRC 6
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