BECKWITH ELECTRIC Syncrocloser M-3410A, Instruction Book

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M-3410A Instruction Book
3–8
3.2 Setpoints and Time Settings
The individual protective functions, along with their
magnitude and timing settings are described in the
following pages. Settings are entered utilizing the
M-3810A IPScom
® for Windows™ or M-3811A
IPScom for Palm OS ® Communications Software.
Enabling a relay protective function consists of
entering the required settings in the individual
function screens. Disabling a protective function
from IPScom for Windows (whether settings have
been entered or not) is accomplished by deselecting
the individual protective function element numbers.
When a protective function is disabled, screen
values are grayed out.
Enabling and disabling relay functions from M-3811A
IPScom for Palm OS is accomplished by selecting
either Enable or Disable.
25 Sync Check
The Synchronism (Sync) Check function (25) is
used to ensure that the voltage magnitude, phase
angle, and frequency of two sources are within
acceptable limits before closing a circuit breaker to
unite them. This function may be applied across
the intertie breaker to ensure that the Dispersed
Generation (DG) is in sync with the Utility, or
across an individual generator breaker to ensure
that the generator is in sync with the bus.
The sync check function has phase angle, delta
frequency, and delta voltage checks.
The sync phase voltage (V
1
) can be selected as
V
AB
or V
BC
. The V
sync
input (denoted as V
2
) must be
connected to the same phase to phase voltage
input as the selected sync phase.
Phase Angle Check
The phase angle check is considered OK when the
selected sync phase voltage (V
1
) and DG voltage
(V
2
) are within the Upper Volt Limit and Lower Volt
Limit window and the measured phase angle is
within the phase angle window.
Phase angle window is defined as twice the Phase
Limit setting. For example, if the Phase Limit is set
at 10 degrees, a phase angle window of 20 degrees
exists between –10 (350) degrees and +10 degrees.
The basic phase angle check is shown in Figures
3-12 and 3-13.
Delta Voltage and Delta Frequency Check
Delta voltage and delta frequency elements may be
individually enabled or disabled, as desired. Delta
voltage check will compare the absolute difference
between the selected sync phase voltage (V1) and
the measured DG voltage (V2) with the Delta Volt
limit setting. Likewise, the delta frequency measures
the frequency difference between V1 and V2 voltage
signals. The logic diagram of the above is shown in
Figures 3-12 and 3-13.
Dead Line/Dead Bus Check
The Dead Volt Limit defines the Hot/Dead voltage
level used in deadline/dead bus closing schemes.
When the measured V2 voltage is equal to or below
the Dead Volt Limit, V2 is considered dead. When
the measured V2 is above the Dead Volt Limit, V2
is considered hot. The opposite side of the breaker
uses the positive sequence voltage measurement
(V1
pos
) for 3-phase consideration in determining hot/
dead detection. Different combinations of hot line/
dead bus closings may be selected, depending on
how the buses are referenced. Figure 3-12 illustrates
enabling/disabling of the dead line/dead bus scheme
through contact inputs.
Dead Line/Dead Bus Check Input Initiate
The Dead V1/Hot V2, Dead V2/Hot V1, and Dead V1/
Dead V2 enable are software switches used to enable
the dead line/dead bus logic. Further conditioning can
be performed on the dead detection logic by selecting
one or more input contacts (Dead Input Initiate) to
control the enabled dead detection element. For
example, if INPUT2 (I2) is selected under the Dead
Input Initiate screen, and both the Dead V1 and Dead
V2 elements are enabled, the dead check timer will
start when INPUT2 is activated, and either V1 Dead
V2 Hot or V1 Hot V2 Dead. This allows for external
control of the desired dead closing scheme. Dead
Input Initiate selections are common to all dead
detection elements. If no inputs are selected under
the Dead Input Initiate screen, and any dead element
is enabled, the dead check timer will start immediately
when the dead condition exists. Figures 3-12 and
3-13 illustrate enabling/disabling of the Dead Line/
Dead Bus scheme through contact inputs.
Eventually, the Dead Line/Dead Bus check, Phase
Angle check, Delta Volt and Delta Frequency checks
all combine through their appropriate timers and are
directed to the programmed 25 output relay. The
overall logic of the Sync Check (25) function is
illustrated in Figures 3-12 and 3-13.
Supervision of 25 by 79
The Sync Check function (25) can be supervised
by the reconnect enable (79) function. The “79
supervise 25” setting (Figure 3-13), if enabled, will
hold both the dead check and sync check timers
reset until the 79 timer expires.