11-24 L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUALBATTERY CHAPTER 11: MAINTENANCE11The standard front panel can be opened to the left once the black plastic sliding latch on the right side has beenpushed up, as shown below.Figure 11-27: Removing module (standard front panel)2. With power to the unit off, disconnect individually the connections at the front and back of the module beforeremoving the module from the chassis.For any Process Card/process bus module in slot H for use with a HardFiber Brick, also remove the two screws at theback that attach the module to the chassis.3. To properly remove a module, pull simultaneously the ejector/inserter clips, located at the top and bottom of themodule. Record the original location of the module to ensure that the same or replacement module is inserted into thecorrect slot. While modules with current input provide automatic shorting of external CT circuits, for CT/VT modules itis recommended to short/isolate external circuits accordingly for maximum safety.4. To properly insert a module, ensure that the correct module type is inserted into the correct slot position. The ejector/inserter clips located at the top and at the bottom of each module must be in the disengaged position as the moduleis smoothly inserted into the slot. Once the clips have cleared the raised edge of the chassis, engage the clipssimultaneously. When the clips have locked into position, the module is fully inserted.11.12 BatteryA battery powers the real time clock on startup of the device.When required, the battery can be replaced. The power supply module contains the battery. The battery type is 3 Vcylindrical.11.12.1 Replace battery for SH/SL power supplyWhen required, the battery can be replaced. The power supply module contains the battery.When adding a module (versus replacing a module), check that settings have not changed. Depending on themodule, settings can reset to default values.The new CT/VT modules can only be used with new CPUs; similarly, old CT/VT modules can only be used with oldCPUs. In the event that there is a mismatch between the CPU and CT/VT module, the relay does not function and aDSP ERROR or HARDWARE MISMATCH error displays.
