GE Industrial Solutions Entellisys 4.0 System User Manual - Manual (Page 71)

Single Point Relay protection 71
5
5.2.2 Overvoltage Relay
The Entellisys system performs the Overvoltage Relay function by comparing the voltage in
each phase to the nominal 1X value of the system voltage. For example, in a 120-V wye system,
nominal 1X is defined to be 120-V phase to neutral.
The relay can be in three states:
•
Pickup – If the voltage in a set number of voltage phases (one, two or all three voltage
phases) is greater than the pickup set point, the relay goes into pickup, and is said to enter
Pickup state
•
Operate – If the relay stays in pickup state for a specified pick up delay time, the system trips
the appropriate circuit breaker or activates an alarm, and the relay is said to be in Operate
state
•
Drop out – The relay drops out of pickup when the voltage drops below 97% of the
programmed threshold. The relay is said to be in Drop out state.
For wye potential transformers, the Overvoltage Relay operates on phase neutral voltage. For
open delta potential transformers, the Overvoltage Relay operates on line-line voltage.
Entellisys uses RMS voltages in the calculations.
The system trips the appropriate circuit breaker or activates an alarm if the voltage is greater
than the pick up set point for the specified time delay.
5.2.2.1 Accuracy
Pickup accuracy is ± 2%.
5.2.2.2 Setup
To set the Trip and Alarm settings for the Overvoltage Relay
1. On the Main Menu, click User Settings, and then select Relay Protection.
2. On the Relay Protection screen, choose the circuit breaker number from the drop-down
menu and click Overvoltage.
The remainder of this section discusses the relay parameters that can be set in the Overvoltage
section of the Relay Protection screen as shown in Figure 5-5.
5.2.2.3 Trip settings
Relay Enabled: Select Enabled to enable the relay.
Pickup: Adjust the overvoltage pickup from 105% to 125% in increments of 1% from the Pickup
Setting drop-down menu.
Delay: Adjust the overvoltage delay from 0.5 to 600 seconds in increments of 0.5 seconds from
the Time Delay drop-down menu.
Phase Requirement: Select from among the following options using the Phase Requirement
drop-down menu:
•
Operate if any one phase is below the pickup threshold
•
Operate if any two phases are below the pickup threshold
•
Operate if all three phases are below the pickup threshold
Open Trip: Select the command issued when the relay operates from the Open Trip drop-down
menu. Options are Open and don't activate lockout and Trip and activate lockout.