Date Code 20010518 Maintenance 10-1
SEL-2020 Instruction Manual
SECTION 10: MAINTENANCE
INTRODUCTION
This section describes the minimal maintenance steps you should follow to keep the SEL-2020
operating properly. This section also includes a guide to troubleshooting and alarm diagnosis.
CALIBRATION
Schweitzer Engineering Laboratories (SEL) performs a calibration of the SEL-2020 clock at the
factory. You do not need to periodically calibrate the clock.
BATTERY REPLACEMENT
A battery maintains the clock (date and time) if the external DC source is lost or removed. The
battery is a 3 V Lithium Carbon Monofluoride coin cell, IEC No. BR2335 or equivalent. At
room temperature (25°C) the battery will discharge for 10 years at rated load.
The battery experiences a low self-discharge rate when the SEL-2020 is powered from an
external source. If the source is lost or disconnected, the battery discharges to keep the internal
clock going. The battery cannot be recharged.
CAUTION
!
There is danger of explosion if the battery is incorrectly replaced.
Replace only with Ray-O-Vac
®
no. BR2335 or equivalent
recommended by manufacturer. Dispose of used batteries
according to the manufacturer’s instructions.
Perform the battery replacement procedure if the SEL-2020 reports a battery failure. You will
also notice that the time and date are incorrect. To change the battery, perform the following
steps:
1. Remove power from the SEL-2020.
2. Remove any cables connected to Port F of the SEL-2020.
3. Remove the front-panel screws and front panel.
CAUTION
!
The SEL-2020 contains devices sensitive to electrostatic
discharge (ESD). When working on the device with front or top
cover removed, work surfaces and personnel must be properly
grounded or equipment damage may result.
4. Locate the battery on the front left-hand side of the main board.
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