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3.2
SEL-400 Series Relays
Instruction Manual
Date Code 20171006
Basic Relay Operations
Inspecting a New Relay
Initial Inspection
Perform the following initial inspection when the relay arrives:
Step 1. Remove the protective wrapping from the relay.
Step 2. Observe the outside of the front cover and the rear panel.
Step 3. Check that no significant scratches or dents are evident on any outer
surface.
Step 4. Confirm that all terminal strips on the rear panel are secure.
Perform the following steps and use care when cleaning the relay:
Step 1. Use a mild soap or detergent solution and a damp cloth to clean the
relay chassis.
Be careful cleaning the front and rear panels because a permanent
plastic sheet covers each panel; do not use abrasive materials,
polishing compounds, or harsh chemical solvents (such as xylene or
acetone) on any relay surface.
Step 2. Allow the relay to air dry, or wipe dry with a soft dry cloth.
Verify Relay Configuration
When you first inspect the relay, confirm that the relay power supply voltage and
nominal ac signal magnitudes are appropriate for your application. Examine the
serial number label on the relay rear panel.
shows a sample rear-panel
serial number label.
shows a serial number label for an SEL-451 with additional I/O in a
4U horizontal chassis. This example serial number label is for a 5 A-per-phase
secondary CT input relay. For information on CT and PT inputs, Do not use this
page for ordering a relay. For ordering information, refer to the SEL-451 Model
Option Table available at selinc.com/products/, or contact your SEL Sales Repre-
sentatives.
The power supply specification in Figure 4.1 indicates that this relay is equipped
with a power supply that accepts a nominal 48–125 Vdc input. This power supply
also accepts a 110–120 Vac input. Refer to the serial number label affixed to the
back of your relay to determine the power supply voltage you should apply to the
relay power supply input terminals. As this label indicates, the voltage source
should be capable of providing at least 35 W for dc inputs and 90 VA for ac
inputs. See
Section 1: Introduction and Specifications
in the product-specific
instruction manual for more information on power supply specifications.
Figure 3.1
Sample Relay Serial Number Label
Part Number
Serial Number
Power Supply Input
Specifications
Secondary Current Input
Secondary Voltage Input
I/O Interface Board(s)
Logic Input Rating
(See Logic Input Ratings, below)
Summary of Contents for SEL-421-4
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