GE IRT51 E, Инструкция по эксплуатации, Страница: 16 / 51

GEK-86038
* should be identical for all three leads.
The resistance of each lead to relays
us�d with 10 ohm RTDs must not exceed 0.25 ohm (1.0 ohm to relays used with 100 ohm
o;" 120 ohm RTDs).
A decrease in the operating point of the re 1 ay of up to 0. 8 o C
can be expected for each ohm of lead run to relays with 10 ohm RTDs. {The decrease
can be up to 0.2oC for each ohm of lead run to relays using 100 ohm or 120 ohm
�
TDs.)
TABLE 8
LEAD WIRE RESISTANCE
LEAD WIRE SIZE OHMS/FT
AWG NO. DIAMETER INCHES AT 25° C
12 0.0808 0.0016
14 0.0640 0.0026
16
0.0508
0.0041
18 0.0403
0.0065
20 0.0320 0.0104
22 0.0253 0.0165
24 0.0201 0.0262
26 0.0159 0.0416
28 0.0126 0.0666
30 0.0100 0.1058
Shou
1
d it become necessary .to switch the re
1
ay from one RTD to another by a
switching scheme, arrange the switching circuit to remove the lead from stud 6
first and restore it last. This procedure will avoid nuisance tripping during the
·�
switching operation.
f.
At the time of installation, visually check the relay for tarnished contacts,
loose screws, foreign matter within the case, or any other physical imperfections.
If any of these are found, they should be corrected immediately.
INSPECTION , ACCEPTANCE TESTS,
PERIOD I C CHECKS AND ROUTINE MAI NTENANCE
Immediately upon receipt of the relay, it should be inspected and tested to
make sure that no damage has been sustained in shipment and that the relay
calibrations have not been disturbed. Also, in view of the vital role of
protective relays in the operation of a power system, it is important that a
periodic test program be followed. The interval between periodic checks will vary
depending upon environment, type of relay and the user1S experience with periodic
testing.
Until the user has accumu
1
a ted enough experience to select the test
interval best suited to his individual requirements, it is suggested that the the
following inspections and tests be performed at the time the relay is received, and
then repeated once a year thereafter.
VISUAL INSPECTION
Remove the relay from its case and check that there are no broken or cracked
parts or any other i nd i cations of damage. Check that the i nterna
1
parts of the
relay are clean and that there is no foreign matter within the relay.
* Revised since last issue
14
www . ElectricalPartManuals
. com
www
. ElectricalPartManuals
. com