BECKWITH ELECTRIC M-6280A, Instruction Book

Page: 284 / 462

Configuration – 4
4–93
Internal 48 Hour Delta Voltage Timer
In the event of a loss of power to the control, when
power is restored the control will compare the
Internal 48 Hour Timer start time to the control’s
internal time. The control will resume timing, taking
the elapsed time the control was without power into
account.
For example:
1. The Timer starts and the start date/time
is stored
2. 3 hours later the control loses power
3. The control is without power for 26 hours
4. When power to the control is restored,
the timer will resume timing with 19
hours remaining.
5. If the time the unit was without power was
≥
48 hours, the Delta Voltage will be set
to ½ the bandwidth value and the Delta
Voltage alarm will be reset.
Delta Voltage in Auto Adaptive Control Mode
In the Auto Adaptive control mode, either Fixed
or Average, the Delta Voltage sets the Open and
Close operational rails that determines when the
control will initiate Open or Close operations. For
this reason, a Delta Voltage alarm is not needed in
these modes.
If a control is performing Install Mode and the final
Close operation in that process occurs when voltage
exceeds the Control Mode Maximum or Minimum
Voltage Limit settings, then that Delta Voltage
measurement will not be considered. The control will
store the need to perform Install Mode again and it
will run the next time power to the control is cycled.
Overview of Auto/Remote Limits and Auto
Control Setting Time Delay Implementation
The Auto/Remote Limits and Auto Control Setting
Time Delays are required to inhibit the capacitor
bank control from unnecessary operations on
temporary voltage excursions and is commonly
set at 30 to 60 seconds. The timer includes
two selectable elements "Definite/Inverse" and
"Integrating/Instant Reset. It is important to note that
Inverse type timer only applies to Voltage Control
Mode. All other modes (VAr and Current) use only
definite type regardless of the timer type setting.
The control will only respond to an over the limit
voltage excursion after the Auto/Remote Limits
and Auto Control Time Delay have timed out. The
Time Delay can be set as an integrating timer or
an instantaneous reset timer upon the voltage
return over the limit condition. As an integrating
timer, it increments during time over the limit and
decrements during time within the limits, but not
below zero.
The Integrating Timer type does not apply to Inverse
Time selection.
The Time Delay can be set to either a Definite or
Inverse delay. The inverse time delay will follow the
curve in Figure 4‑48, Inverse Time Delay Curve.

NOTE: When in Remote Control Mode the Open
Voltage becomes Overvoltage Limit and
Close Voltage becomes Undervoltage
Limit.
Inverse Time Example
Open Voltage 121.5 V
Close Voltage 118.5 V
Inverse Time Delay Setting 120 s
∆
V = (Open Voltage – Close Voltage) = 1.5 V
2
∆
V = (121.5 – 118.5) = 1.5 V
2
Vin = 123 V
Voltage deviation in multiples of
∆
V
= [V
in
– Effective Bandcenter]/
∆
V
= (123 – 120)/1.5
=2
Time delay from Figure 4‑47
= 50% of Inverse Time Delay setting
= 60 sec