Frequency protection (81o/u), Underfrequency (81u), Overfrequency (81o) – Winco DGC-2020 User Manual

Page 117: Frequency protection (81o/u) -47, Figure 4-44. frequency protection settings -47

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A

Pickup: Adjustable from 5 to 100 Vac in 1 Vac increments.

B

Activation Delay: Adjustable from 0 to 30 s in 0.1 s increments.

C

Alarm Configuration: None, Alarm, Pre-Alarm, or Status Only.

D

Hysteresis: Adjustable from 1 to 5 Vac in 1 Vac increments.

Frequency Protection (81O/U)
Two sets of frequency protection settings are provided: one for underfrequency (81U) and one for
overfrequency (81O).

Underfrequency (81U)
An underfrequency condition is annunciated when the generator frequency decreases below the 81U
pickup setting

A

for the duration of the 81U activation delay setting

B

. An underfrequency annunciation can

be user-selected to trigger a pre-alarm

C

(warning) or alarm

C

(shutdown). An underfrequency annunciation

can also be user-configured to close a programmable output.
A voltage-based inhibit setting

D

prevents an 81U trip from occurring during an underfrequency condition

associated with system startup.
The hysteresis setting

E

functions as an underfrequency dropout by preventing rapid switching of the

pickup output.

Overfrequency (81O)
When the generator frequency increases above the 81O pickup setting

F

for the duration of the 81O

activation delay setting

G

, an overfrequency condition is annunciated. An overfrequency annunciation can

be user-selected to trigger a pre-alarm

H

(warning) or alarm

H

(shutdown). An overfrequency condition can

also be user configured to close a programmable output.
The hysteresis setting

I

functions as an overfrequency dropout by preventing rapid switching of the pickup

output.
The element is disabled when Alarm Configuration is set to “None”. Element status is available in
BESTlogic+ Programmable Logic when “Status Only” is selected.
BESTCOMSPlus frequency protection settings (DGC-2020, Generator Protection, Frequency) are
illustrated in Figure 4-44.

Figure 4-44. Frequency Protection Settings

A

Underfrequency Pickup: Adjustable from 45 to 66 Hz in 0.1 Hz increments for 50/60 Hz controllers

(style number x1xxxxxxxx). Adjustable from 360 to 440 Hz in 0.1 Hz increments for 400 Hz controllers
(style number x2xxxxxxxx).

B

Underfrequency Activation Delay: Adjustable from 0 to 30 s in 0.1 s increments.

C

Underfrequency Alarm Configuration: None, Alarm, Pre-Alarm, or Status Only.

D

Underfrequency Inhibit Volts: Adjustable from 70 to 576 Vac in 1 Vac increments.

E

Hysteresis: Adjustable from 0.1 to 40 Hz in 0.1 Hz increments.

F

Overfrequency Pickup: Adjustable from 45 to 65 Hz in 0.1 Hz increments for 50/60 Hz controllers (style

number x1xxxxxxxx). Adjustable from 360 to 440 Hz in 0.1 Hz increments for 400 Hz controllers (style
number x2xxxxxxxx).

G

Overfrequency Activation Delay: Adjustable from 0 to 30 s in 0.1 s increments.

9400200990 Rev K

DGC-2020 BESTCOMSPlus Software

4-47

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