GE B90 Instruction Manual

Also see for B90: Communications manual Communications guide Instruction manual Instruction manual Instruction manual

Contents

5-4 B90 LOW IMPEDANCE BUS DIFFERENTIAL SYSTEM – INSTRUCTION MANUALOVERVIEW CHAPTER 5: SETTINGS5For voltage elements, the primary base quantity is the nominal phase-to-phase primary voltage of the protected systemprovided that the VT ratio setting is set to the nominal ratio of the VTs and the secondary voltage setting is set to thephase-to-phase voltage seen by the relay when the voltage of the protected system in nominal. The UR uses theconvention that nominal voltages in a three-phase system are phase-to-phase voltages.For example, on a system with a 13.8 kV nominal primary voltage, the base quantity is 13800 V. With 14400:120 V delta-connected VTs, the secondary base quantity and secondary voltage setting is:Eq. 5-1For 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.• 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 faceplate 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.