3.52
SEL-387-0, -5, -6 Relay
Instruction Manual
Date Code 20050919
Differential, Restricted Earth Fault, Thermal, and Overcurrent Elements
Thermal Element (SEL-387-6 Relay)
The default value from
is 0.08 hours. You can select other values
from within a range of 0–2 hours. The default values listed in
are
from IEEE C57.92-1981, Tables 2 and 4.
Oil Exponent (EXPnxy)
Range: 0.1–5, in 0.1 steps
This exponent is a constant that the thermal element uses in calculating
ultimate top-oil rise over ambient temperature (
∆Θ
TO
).
The default values listed in
are from IEEE C57.92-1981, Tables 2
and 4. If specific values for a particular transformer are known, you can enter
values from within a range of 0 to 5.
Winding Exponent (EXPmxy)
Range: 0.1–5, in 0.1 steps
This exponent is a constant that the thermal unit uses in calculating ultimate
hot-spot conductor rise over top-oil temperature (
∆Θ
H
).
The default values listed in
are from IEEE C57.92-1981, Tables 2
and 4. If specific values for a particular transformer are known, you can enter
values from within a range of 0 to 5.
Application Guideline,
Using the SEL-2030
to Send Temperature
Data to the SEL-387-6
While the SEL-387-5, SEL-387-6 relays can communicate directly with the
SEL-2600A for gathering temperature readings, some applications may use
the SEL-2030 communications processor for retrieving the temperature data
from the SEL-2600A.
The SEL-387-6 obtains temperature information via one of its serial ports.
The relay may receive data from as many as four temperature transducers: a
single ambient temperature transducer and one transducer for top-oil
temperature from each of three single-phase transformers. These data could
come from an SEL-2032 or an SEL-2030 Communications Processor, which
receives the temperature data from either an SEL-2600A RTD Module or a
PLC (see
). The SEL communications processor must receive the
temperature data in Modbus
®
, SEL Fast Messaging, or ASCII protocol. The
SEL communications processor passes these data on to the SEL-387-6 in the
form of an SEL Fast Message. While the SEL-387-6 can receive temperature
data at any rate, the thermal element uses these data only once a minute.
Please refer to SEL
Application Guide 2000-07, Connection and
Configuration of an
SEL
Communications Processor and
SEL
-2600A to
Obtain Measured Ambient and Top-Oil Temperatures for
SEL-387
-6 Relay
or
C = 0.1323 • (weight of core and coil assembly in kilograms)
+ 0.0882 • (weight of tank and fitting in kilograms)
+ 0.3513 • (liters of oil)
P
r
= total loss at rated load (watts)
THor = top-oil rise over ambient at rated load
where:
1 kg = 2.2046 pounds
1 gallon = 3.785 liters
Summary of Contents for SEL-387-0
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