2-10
Installation
Date Code 20020129
SEL-387E Instruction Manual
chassis is removed, the chassis ground connection can be made with the size #6-32 screw. The
grounding terminal of either relay version connects directly to relay chassis ground.
Power Supply
Connect rear-panel terminals (Z25) and – (Z26) to a source of control voltage. Control
power passes through these terminals to a fuse(s) and to the switching power supply. The
control power circuitry is isolated from the frame ground. The 24/48 V power supply is polarity
sensitive. Refer to
Section 1: Introduction and Specifications
for power supply voltage ranges.
Current Transformer Inputs
Connect current inputs to the three sets of current input terminals. Note that the CT shorting
connectors providing current connections to Connectorized relays install in only one orientation.
Note also that the current input terminals on both terminal block and Connectorized relays have a
mark at one terminal per phase to indicate polarity. Each current input is independent of the
other two inputs. Current inputs are designated IAW1, IBW1, ICW1; IAW2, IBW2, ICW2; and
IAW3, IBW3, ICW3.
Note:
When installing CT shorting connectors, ensure that you secure each connector to the
relay chassis with the screws at each connector end. When removing a CT shorting
connector, pull it straight away from the relay rear panel. Removing a shorting
connector causes internal mechanisms within the connector to individually short out
each power system current transformer.
Potential Transformer Inputs
Any of the single-phase voltage inputs (i.e., VA-N, VB-N, or VC-N) can be connected to
voltages up to 300 V RMS continuous. Figure 2.8 shows an example of wye-connected voltages.
Frequency is determined from the voltages connected to terminal VA-N. Volts/hertz is
determined from the largest per-winding volts/hertz measurement (see
Volts/Hertz Element
Specifications
in
Section 3: Differential, Restricted Earth Fault, Overcurrent, Voltage, and
Frequency Elements
).
Note the signal labels (VA, VB, VC, N) on terminals Z19 through Z22. Figure 2.8 shows the
internal connection for terminals VA, VB, VC, and VN.
Optoisolated Inputs
Connect control input wiring to the six standard inputs IN101–IN106 and to any of the interface
board optoisolated inputs IN201–IN208 you need for your application.
All control inputs are dry optoisolated inputs and are not polarity dependent. Specify a
nominal-rated control voltage of 48, 110, 125, or 250 Vdc for level-sensitive and 24 Vdc for
nonlevel-sensitive when ordering. To assert an input, apply nominal-rated control voltage to the
terminals assigned to that input. A terminal pair is brought out for each input. Refer to the
General Specifications
in
Section 1: Introduction and Specifications
for optoisolated input
ratings. There are no internal connections between inputs. ON and OFF values normally are
within one volt of each other, in the indicated range.
