GE M60 Instruction Manual page 327

CHAPTER 5: SETTINGS
– For all other angles, the element output is logic "1"
• Once the voltage memory has expired, the phase overcurrent elements under directional control can be set to block or
trip on overcurrent as follows:
– When
BLOCK WHEN V MEM EXP
overcurrent element under directional control when voltage memory expires
– When
BLOCK WHEN V MEM EXP
under directional control when voltage memory expires
In all cases, directional blocking is permitted to resume when the polarizing voltage becomes greater than the 'polarizing
voltage threshold.'
Settings
— This setting is used to select the source for the operating and polarizing signals. The
PHASE DIR 1 SIGNAL SOURCE
operating current for the phase directional element is the phase current for the selected current source. The polarizing
voltage is the line voltage from the phase VTs, based on the 90° or 'quadrature' connection and shifted in the leading
direction by the element characteristic angle (ECA).
— This setting is used to select the element characteristic angle, i.e. the angle by which the polarizing
PHASE DIR 1 ECA
voltage is shifted in the leading direction to achieve dependable operation. In the design of the UR-series elements, a block
is applied to an element by asserting logic 1 at the blocking input. This element should be programmed via the ECA setting
so that the output is logic 1 for current in the non-tripping direction.
PHASE DIR 1 POL V THRESHOLD
measurement is reliable. The setting is based on VT accuracy. The default value is "0.700 pu."
PHASE DIR 1 BLOCK WHEN V MEM EXP
memory. When set to "Yes," the directional element blocks the operation of any phase overcurrent element under
directional control, when voltage memory expires; when set to "No," the directional element allows tripping of phase
overcurrent elements under directional control.
The phase directional element responds to the forward load current. In the case of a following reverse fault,
the element needs some time—in the order of 8 ms—to establish a blocking signal. Some protection elements,
NOTE such as instantaneous overcurrent, respond to reverse faults before the blocking signal is established.
Therefore, a coordination time of at least 10 ms must be added to all the instantaneous protection elements
under the supervision of the phase directional element. If current reversal is of a concern, a longer delay—in
the order of 20 ms—is needed.
M60 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
is set to "Yes," the directional element blocks the operation of any phase
is set to "No," the directional element allows tripping of phase overcurrent elements
— This setting is used to establish the minimum level of voltage for which the phase angle
— This setting is used to select the required operation upon expiration of voltage
GROUPED ELEMENTS
5
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