GE L30 Instruction Manual

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Contents

GE L30 Instruction Manual Manual pdf 219 page image

CHAPTER 5: SETTINGS OVERVIEWL30 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL 5-55For wye-connected VTs, the primary and secondary base quantities are as before, but the secondary voltage setting (herea phase-to-ground value) is:Eq. 5-2Many settings are common to most elements, outlined as follows:• FUNCTION setting — This setting programs the element to operate when selected as “Enabled.” The factory default is“Disabled.” Once “Enabled,” any element associated with the function becomes active and all options becomeavailable.• NAME setting — This setting is used to uniquely identify the element.• SOURCE setting — This setting is used to select the AC source to be monitored. See the Introduction to AC Sourcessection later.• PICKUP setting — For simple elements, this setting is used to program the level of the measured parameter above orbelow which the pickup state is established. In more complex elements, a set of settings can be provided to define therange of the measured parameters that cause the element to pick up.• PICKUP DELAY setting — This setting sets a time-delay-on-pickup, or on-delay, for the duration between the pickupand operate output states.• RESET DELAY setting — This setting is used to set a time-delay-on-dropout, or off-delay, for the duration between theoperate output state and the return to logic 0 after the input transits outside the defined pickup range.• BLOCK setting — The default output operand state of all comparators is a logic 0 or “flag not set.” The comparatorremains in this default state until a logic 1 is asserted at the RUN input, allowing the test to be performed. If the RUNinput changes to logic 0 at any time, the comparator returns to the default state. The RUN input is used to supervisethe comparator. The BLOCK input is used as one of the inputs to RUN control.• TARGET setting — This setting is used to define the operation of an element target message. When set to "Disabled,"no target message or illumination of a front panel LED indicator is issued upon operation of the element. When set to“Self-Reset,” the target message and LED indication follow the operate state of the element and self-resets once theoperate element condition clears. When set to “Latched,” the target message and LED indication remains visible afterthe element output returns to logic 0 until a RESET command is received by the relay.• EVENTS setting — This setting is used to control whether the pickup, dropout, or operate states are recorded by theevent recorder. When set to “Disabled,” element pickup, dropout, or operate are not recorded as events. When set to“Enabled,” events are created for PKP (pickup) DPO (dropout) OP (operate)The DPO event is created when the measure and decide comparator output transits from the pickup state (logic 1) tothe dropout state (logic 0). This can happen when the element is in the operate state if the reset delay time is not zero.Not every operand of a given element in a UR relay generates events, only the major output operands. Elements,asserting output per phase, log operating phase output only, without asserting the common three-phase operandevent.5.2.2 Introduction to AC sources5.2.2.1 BackgroundThe L30 can be used on systems with breaker-and-a-half or ring bus configurations.In these applications, each of the two three-phase sets of individual phase currents (one associated with each breaker) canbe used as an input to a breaker failure element. The sum of both breaker phase currents and 3I_0 residual currents canbe required for the circuit relaying and metering functions. Two separate synchrocheck elements can be programmed tocheck synchronization between two different buses VT and the line VT. These requirements can be satisfied with a singleL30, equipped with sufficient CT and VT input channels, by selecting proper parameter to measure. A mechanism isprovided to specify the AC parameter (or group of parameters) used as the input to protection/control comparators and