2.19
Date Code 20080918
Instruction Manual
SEL-749M Relay
Installation
Field Serviceability
Field Serviceability
The SEL-749M firmware may be upgraded in the field; refer to
for firmware upgrade instructions. You may
know when a self-test failure has occurred by configuring an output contact to
create a diagnostic alarm as explained in
Section 4: Protection and Logic
. By using the metering functions, you may know if the analog
front-end (not monitored by relay self-test) is functional. Refer to
for detailed testing and troubleshooting
information.
The only two components that may be replaced in the field are the power
supply fuse and the real-time clock battery. A lithium battery powers the clock
(date and time) if the external power source is lost or removed. The battery is a
3 V lithium coin cell, Ray-O-Vac
®
BR2335 or equivalent. At room
temperature (25°C), the battery will operate nominally for 10 years at rated
load. When the relay is powered from an external source, the battery
experiences a low self-discharge rate. Thus, battery life may extend well
beyond 10 years. The battery cannot be recharged.
Fuse Replacement
To replace the power supply fuse, perform the following steps:
Step 1. De-energize the relay.
Step 2. Remove the four rear-panel screws and the relay rear panel.
Step 3. Remove the Slot
A
printed circuit board.
Step 4. Locate the fuse on the board.
Step 5. Remove the fuse from the fuse holder.
Step 6. Replace the fuse with a time delay, 5 x 20 mm, 3.15 A, high-
breaking capacity, 250 V fuse (T3.15 H 250 V).
Step 7. Insert the printed circuit board into Slot
A
.
Step 8. Replace the relay rear panel and energize the relay.
Real-Time Clock
Battery Replacement
To replace the real-time clock battery, perform the following steps:
Step 1. De-energize the relay.
Step 2. Remove the four rear-panel screws and the relay rear panel.
Step 3. Remove the Slot B printed circuit board.
Step 4. Locate the battery clip (holder) on the board.
Step 5. Carefully remove the battery from beneath the clip.
Properly dispose of the old battery.
Step 6. Install the new battery with the positive (+) side facing up.
Step 7. Insert the printed circuit board into Slot B.
Step 8. Replace the relay rear panel and energize the relay.
Step 9. Set the relay date and time.
Equipment components are sensitive
to electrostatic discharge (ESD).
Undetectable permanent damage
can result if you do not use proper
ESD procedures. Ground yourself,
your work surface, and this
equipment before removing any
cover from this equipment. If your
facility is not equipped to work with
these components, contact SEL
about returning this device and
related SEL equipment for service.
!
CAUTION
Disconnect or de-energize all
external connections before opening
this device. Contact with hazardous
voltages and currents inside this
device can cause electrical shock
resulting in injury or death.
!
DANGER
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.
!
CAUTION
Содержание SEL-749M
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