GE Multilin L90 Line Current Differential System 5-2875 SETTINGS 5.8 INPUTS/OUTPUTS5The L90 latching output contacts are mechanically bi-stable and controlled by two separate (open and close) coils. As suchthey retain their position even if the relay is not powered up. The relay recognizes all latching output contact cards and pop-ulates the setting menu accordingly. On power up, the relay reads positions of the latching contacts from the hardwarebefore executing any other functions of the relay (such as protection and control features or FlexLogic™).The latching output modules, either as a part of the relay or as individual modules, are shipped from the factory with alllatching contacts opened. It is highly recommended to double-check the programming and positions of the latching con-tacts when replacing a module.Since the relay asserts the output contact and reads back its position, it is possible to incorporate self-monitoring capabili-ties for the latching outputs. If any latching outputs exhibits a discrepancy, the LATCHING OUTPUT ERROR self-test error isdeclared. The error is signaled by the LATCHING OUT ERROR FlexLogic™ operand, event, and target message.• OUTPUT H1a OPERATE: This setting specifies a FlexLogic™ operand to operate the ‘close coil’ of the contact. Therelay will seal-in this input to safely close the contact. Once the contact is closed and the RESET input is logic 0 (off),any activity of the OPERATE input, such as subsequent chattering, will not have any effect. With both the OPERATE andRESET inputs active (logic 1), the response of the latching contact is specified by the OUTPUT H1A TYPE setting.• OUTPUT H1a RESET: This setting specifies a FlexLogic™ operand to operate the ‘trip coil’ of the contact. The relaywill seal-in this input to safely open the contact. Once the contact is opened and the OPERATE input is logic 0 (off), anyactivity of the RESET input, such as subsequent chattering, will not have any effect. With both the OPERATE and RESETinputs active (logic 1), the response of the latching contact is specified by the OUTPUT H1A TYPE setting.• OUTPUT H1a TYPE: This setting specifies the contact response under conflicting control inputs; that is, when both theOPERATE and RESET signals are applied. With both control inputs applied simultaneously, the contact will close if set to“Operate-dominant” and will open if set to “Reset-dominant”.Application Example 1:A latching output contact H1a is to be controlled from two user-programmable pushbuttons (buttons number 1 and 2). Thefollowing settings should be applied.Program the Latching Outputs by making the following changes in the SETTINGS ÖØ INPUTS/OUTPUTS ÖØ CONTACT OUT-PUTS Ö CONTACT OUTPUT H1a menu (assuming an H4L module):OUTPUT H1a OPERATE: “ PUSHBUTTON 1 ON”OUTPUT H1a RESET: “ PUSHBUTTON 2 ON ”Program the pushbuttons by making the following changes in the PRODUCT SETUP ÖØ USER-PROGRAMMABLE PUSHBUT-TONS ÖØ USER PUSHBUTTON 1 and USER PUSHBUTTON 2 menus:PUSHBUTTON 1 FUNCTION: “Self-reset” PUSHBUTTON 2 FUNCTION: “Self-reset”PUSHBTN 1 DROP-OUT TIME: “0.00 s” PUSHBTN 2 DROP-OUT TIME: “0.00 s”Application Example 2:A relay, having two latching contacts H1a and H1c, is to be programmed. The H1a contact is to be a Type-a contact, whilethe H1c contact is to be a Type-b contact (Type-a means closed after exercising the operate input; Type-b means closedafter exercising the reset input). The relay is to be controlled from virtual outputs: VO1 to operate and VO2 to reset.Program the Latching Outputs by making the following changes in the SETTINGS ÖØ INPUTS/OUTPUTS ÖØ CONTACT OUT-PUTS Ö CONTACT OUTPUT H1a and CONTACT OUTPUT H1c menus (assuming an H4L module):OUTPUT H1a OPERATE: “VO1” OUTPUT H1c OPERATE: “VO2”OUTPUT H1a RESET: “VO2” OUTPUT H1c RESET: “VO1”Since the two physical contacts in this example are mechanically separated and have individual control inputs, they will notoperate at exactly the same time. A discrepancy in the range of a fraction of a maximum operating time may occur. There-fore, a pair of contacts programmed to be a multi-contact relay will not guarantee any specific sequence of operation (suchas make before break). If required, the sequence of operation must be programmed explicitly by delaying some of the con-trol inputs as shown in the next application example.Application Example 3:A make before break functionality must be added to the preceding example. An overlap of 20 ms is required to implementthis functionality as described below:
