DECS-100 BESTCOMS for Windows
®
OS
5-16
Setpoint - Current (A). This setting defines the field current setpoint when operating in FCR mode. The
current setpoint can also be entered at the Setting Adjustments screen, Setpoint tab, Field Current Regulator
(FCR) - FCR Setpoint. Current values from 0 to 7 Adc may be entered in increments of 0.01 Adc. The
background color of this field is green when operating in FCR mode.
Setpoint - Var (% of nom.). This setting determines the level of generator vars maintained by the DECS-100
when operating in var mode. The var setpoint can also be entered at the Setting Adjustments screen,
Setpoint tab, Reactive Power Control (VAR) - VAR Setpoint (% of nom.). The background color of this field
is green when the DECS-100 is operating in AVR mode and is regulating the var setpoint.
Setpoint - Power Factor. This setting determines the level of power factor regulation maintained by the
DECS-100. The power factor setpoint can also be entered at the Setting Adjustments screen, Setpoint tab,
Power Factor Control (PF) - PF Setpoint. Power Factor setpoint values are adjustable from -0.6 to -1 (1) or
0.6 to +1 in 0.001 increments. The background color of this field is green when the DECS-100 is operating
in AVR mode and is regulating the power factor setpoint.
Voltage Matching. The Voltage Matching controls and indicators consist of two buttons and two adjacent
indicators. Clicking the ON button changes the color of the adjacent ON indicator to green and enables
voltage matching by the DECS-100. When Voltage Matching is enabled, the DECS-100 automatically adjusts
the field current to match the generator output voltage with the bus voltage prior to synchronizing. In order
for Voltage Matching to be enabled, the following conditions must be met.
The Parallel Generator Compensation Contacts (terminals 52L and 52M) must be shorted.
The DECS-100 Voltage Matching input must be shorted (terminals VM and VMC).
Var/PF control must be disabled by shorting terminals 52J and 52K (open breaker).
The DECS-100 must be operating in AVR mode.
Clicking the OFF button changes the color of the adjacent OFF indicator to red and disables the voltage
matching function.
Control Mode. Clicking the AVR button changes the color of the adjacent AVR indicator to green and enables
the AVR operating mode. When operating in AVR mode, the DECS-100 regulates the generator output
voltage at the AVR setpoint. Clicking the FCR button changes the color of the adjacent FCR indicator to
green and enables the FCR operating mode. When operating in FCR mode, the DECS-100 maintains the
field current at the FCR setpoint. Enabling the FCR mode turns off Voltage Matching.
Fine Adjustment. Raise and Lower buttons control the fine adjustment of the voltage setpoint. These buttons
perform the same function as closing the appropriate set of contacts connected to the External Adjust
terminals (6D and 7 to decrease, 6U and 7 to increase) of the DECS-100. Each click of the Raise button
increases the voltage setpoint 0.01 volts; each click of the Lower button decreases the voltage setpoint 0.01
volts. The minimum and maximum limits for fine adjustment of the voltage setpoint are controlled by the
Regulator Sensing Voltage setting (System Configuration screen) and the Fine Voltage Adjustment - Band
setting (Setting Adjustments screen). Fine adjustment of the voltage setpoint can be increased/decreased
no higher/lower than the Regulator Sensing Voltage setting plus/minus the Band setting. For example, a
Regulator Sensing Voltage setting of 100 volts and a Band setting of 10 percent allows the Fine Adjustment
function to increase the voltage setpoint to a maximum of 110 volts and decrease the voltage setpoint to a
minimum of 90 volts.
Alarm/Status Tab
The Alarm/Status tab indicators provide the status of DECS-100 protection functions, control modes, and
contact inputs. Alarm/Status tab indicators are illustrated in Figure 5-18 and are described in the following
paragraphs.
Protection Alarms. Five Protection Alarm indicators provide the status of DECS-100 protection functions.
Alarm indicators include Overexcitation Shutdown, Overexcitation Limiting, Underfrequency, Generator
Overvoltage, and Loss of Generator Sensing. When a DECS-100 protection function detects an alarm
condition, the appropriate indicator changes from black to red.
Control Status. Two Control Status indicators indicate when the VAR/PF and Manual modes are active. The
Manual Mode Active indicator changes from black to red when the FCR control mode is active. The VAR/PF
Mode Active indicator changes from black to red when the DECS-100 is operating in AVR mode and
correction of power factor or vars is selected.