Basler Electric BE1-11t - Manual (Page 74)

62 9424200995 Rev H
Pickup and Trip
The Pickup output occurs first, followed by the Trip output.
Pickup
The Pickup output becomes true when the measured frequency decreases below (underfrequency
protection) or increases above (overfrequency protection) the frequency threshold established by the
Pickup setting for three consecutive sensing voltage cycles. In BESTlogicPlus, the Pickup output can be
connected to other logic elements to annunciate the condition, control other elements in logic, and start
the fault recorder (logic element FAULTTRIG).
Assertion of the Pickup output initiates a timer that begins timing to a trip. The duration of the timer is
established by the Time Delay setting. A Time Delay setting of zero (0) makes the 81 element
instantaneous with no intentional time delay.
If the pickup condition subsides before the element delay expires, the timer and Pickup output are reset,
no corrective action is taken, and the element is rearmed for any other occurrences of underfrequency or
overfrequency.
Trip
The Trip output becomes true if an underfrequency or overfrequency pickup condition persists for the
duration of the element Time Delay setting. In BESTlogicPlus, the Trip output can be connected to other
logic elements and to a physical relay output to annunciate the condition and to initiate corrective action.
If a target is enabled for the element, the BE1-11t will record a target when the Trip output becomes true.
See the
Fault Reporting chapter for more information about target reporting.
Voltage Inhibit
The Voltage Inhibit setting impedes underfrequency/overfrequency element operation during
undervoltage conditions that may occur during equipment startup. This setting is expressed in primary or
secondary voltage depending on the Settings Display Mode selected on the General Settings/Display
Units settings screen in BESTCOMSPlus and its unit of measure depends upon the phase VT connection
setting. For four-wire or phase-to-neutral sensing connections that inhibit level is expressed in Vpn. For
three-wire or phase-to-phase sensing connections the inhibit level is expressed in Vpp.
Element Blocking
The Block input provides logic-supervision control of the element. When true, the Block input disables the
element by forcing the Trip and Pickup outputs to logic 0 and resetting the element timer. Connect the
element Block input to the desired logic in BESTlogicPlus. When the element is initially selected from the
Elements view, the default condition of the Block input is a logic 0.
Frequency Rate-of-Change Protection
When a source of DG is suddenly separated from the electric utility, the frequency rate-of-change (ROC)
will increase or decrease rapidly. Frequency ROC protection provides high-speed detection of an
islanding situation that may not be detected by overfrequency or underfrequency protection. A frequency
ROC protection element can be used for load shedding in conjunction with an underfrequency protection
element to accelerate shedding during a substantial overload or inhibit shedding following a sudden,
transient decrease in frequency. An 81 element can be configured to respond to positive ROC, negative
ROC, or either condition.
Any of the eight 81 elements can be configured for frequency rate-of-change (ROC) protection.
Mode
An 81 element is configured for rate-of-change protection, only positive rate-of-change protection, or only
negative rate-of-change protection through the Mode setting.
Frequency (81) Protection BE1-11t