Table of Contents
Advertisement
GEI-83910
GDIX Unit Pickup: Using the test connections shown in Figure 10, the unit
should pick up at 80% or less of the DC voltage shown on the nameplate.
With rated
voltage suddenly applied, the unit should pick up in 16-18 milliseconds.
PERIODIC CHECKS AND ROUTINE MAINTENANCE
In vi ew of the vital role of protecti ve re 1 ays in the operat i on of a power
system it is important that a periodic test program be followed.
It is recognized
that the i nterva 1 between peri odi c checks wi 11 vary dependi ng upon envi ronment,
type of relay, and the user's experience with periodic testing.
Until the user has
accumulated enough experience to select the test interval best suited to his
individual requirements it is suggested that the following points be checked once a
year.
MECHANICAL CHECKS
Operate the contacts by hand and check that the contacts are making with
proper wipe.
The barrel-type contacts are marked with a letter on the rear of the
barrel that designates the amount of wipe.
Unit
Contact
Stamping
Wipe
Top
Left
H
.013-.018
Middle
Left
L
.002-.004
Middle
Right
L
.002-.004
Bottom
Right
L
.002-.004
Bottom
Left
S
.004-.009
The wipe is the distance the spiral contact can move into the barrel before it
hits the diaphragm, as shown in Figure 6.
This can be changed by adjusting the
flat spiral spring until the proper spacing is obtained.
Examine the contact surfaces for signs of tarnishing or corrosion.
Fine
silver contacts should be cleaned with a burnishing tool that consists of a
flexible strip of metal with an etch-roughened surface.
Burnishing tools designed
especially for cleaning relay contacts can be obtained from the factory.
Do not
use knives, files, abrasive paper or cloth of any kind to clean relay contacts.
When burnishing the low-gradient G1 unit contacts, exercise additional caution
to avoid damaging the delicate leaf springs to which the contacts are fastened.
ELECTRICAL TESTS
Connect the relay as shown in Figure 9 and check that the pi ckup of the G1
unit is within ±5% of the original setting.
Next check that the clutch setting is
within ±5% of the original setting.
Repeat the tests for the G2 and GO units,
using the test diagrams as shown in Figure 9.
Connect the relay as shown in Figure 10 and check that the pickup of the GD1X
unit is within ±5% of the original pickup voltage.
14
Advertisement
Table of Contents
