Date Code 20001006 Installation 2-21
SEL-351 Instruction Manual
1. The voltage inputs do not need to be connected. Voltage is needed for voltage elements, synchronism check
elements, frequency elements, voltage-polarized directional elements, fault location, metering (i.e., voltage, MW,
MVAR), and frequency tracking.
2. Although automatic reclosing is probably not needed in this example, output contact OUT2 can close the circuit
breaker via initiation from various means (serial port communications, optoisolated input assertion, etc.), with
desired supervision (e.g., hot bus check).
3. For sensitive earth fault (SEF) applications, the SEL-351 Relay should be ordered with channel IN rated at 0.05 A
nominal. See current input specifications in the General Specifications subsection in Section 1: Introduction and
Specifications. See neutral ground overcurrent element pickup specifications in Section 3: Overcurrent, Voltage,
Synchronism Check, Frequency, and Power Elements.
Figure 2.11: SEL-351 Relay Provides Overcurrent Protection for a Delta-Wye Transformer
Bank
Courtesy of NationalSwitchgear.com
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