2-12
Installation
Date Code 20020129
SEL-387E Instruction Manual
provides fiber-optic links between devices for electrical isolation and long-distance signal
transmission. Call the factory for further information on these products.
Table 2.1: SEL-387E Relay Communication Cable Numbers
SEL-387E Port #
Connect to Device
(gender refers to the device)
SEL Cable #
2, 3, 4
PC, 25-Pin Male (DTE)
C227A
2, 3, 4
PC, 9-Pin Male (DTE)
C234A
2, 3
SEL-2020 or SEL-2030 without IRIG-B
C272A
2
SEL-2020 or SEL-2030 with IRIG-B
C273A
2
SEL-IDM, Ports 2 through 11
Requires a C254 and C257 cable
2, 3
Modem, 5 Vdc Powered (pin 10)
C220*
2, 3
Standard Modem, 25-Pin Female (DCE)
C222
* The 5 Vdc serial port jumper must be installed to power the modem using C220 (see
Clock Synchronization, IRIG-B
Refer to Table 2.1 for a list of cables that you can purchase from SEL for various time-
synchronizing applications.
The SEL-387E Relay accepts a demodulated IRIG-B format signal for synchronizing an internal
clock to some external source such as the SEL-2020 or SEL-2030 Communications Processor,
SEL-IDM, or satellite time clock. Connect the IRIG-B source to the relay through the
connectors for serial Ports 1 or 2. Refer to the port pin definition of each port for the appropriate
connection.
T
YPICAL
AC/DC C
ONNECTION
D
IAGRAMS
Figure 2.8 and Figure 2.12 represent the ac and dc connections for a typical three-winding
transformer application. The transformer is an autotransformer with a delta tertiary whose
terminals also have been brought out through bushings and are included in the differential zone
of protection. Referring to Figure 2.8, the current transformers for all windings are wye
connected, with their polarity marks facing away from the transformer. Their outputs are taken
to the polarity ends of the relay current inputs, with the nonpolarity ends of the inputs connected
to the CT neutral and ground. A single safety-ground point should be used, as shown. (If current
transformers are delta connected, the nonpolarity ends of the relay current inputs must be wired
together, and should be connected to the common ground point/neutral.)
This transformer example is used later for calculating relay settings; see
Section 6: Setting the
Relay
. This example forms the basis for most of the factory default settings stored in the relay
before shipment.
