Jogging Block Elements; Figure 4.4 Ground Fault Currents Using A Window Ct; Table 4.16 Jogging Block Element Settings - Siemens SIMPRO-100 Instruction Manual

SIMPRO-100
element will quickly detect and trip for motor
ground faults, but prevent misoperation due
to unequal breaker or contactor pole
closing times.
Figure 4.4 Ground Fault Currents Using a
Window CT
When a ground fault CT is not available, either
use the 50G residual overcurrent elements or
connect the IN input residually, as in Figure 2.7,
page 30. Set the Level 1 O/C Pickup between
one-half and one-fifth of the full load phase
current and set the Level 1 Time Delay equal to
0.2 seconds. Set the Level 2 element more
sensitively, but with a longer time delay. The long
time delay allows the sensitive Level 2 element to
ride through the false residual current that can be
caused by phase CT saturation during motor
starting.
Note: Phase CT ratios are typically higher than
ground CT ratios. For this reason, the
relay sensitivity to motor ground faults is
less when IN is connected residually than
if IN is connected to the secondary
winding of an appropriate ground CT. A
separate ground fault detection method
should be used if a ground CT is not
available in applications where resistance
grounding reduces available ground fault
current.
PRIM-2400C
Use the negative-sequence overcurrent element
in addition to or instead of the 46 Current
Unbalance Element to detect phase-to-phase
faults, single phasing, and heavy motor
unbalance. Sensitive unbalance protection is
provided by setting the Negative-Seq. O/C Pickup
(50QP) equal to 0.1 • ITAP with a 4-second time
delay.
4.4.3

Jogging Block Elements

Setting Prompt Setting Range
Maximum Number
OFF, 1 – 15
of Starts per Hour
Minimum Time
OFF, 1 – 150 min
Between Starts

Table 4.16 Jogging Block Element Settings

When the protected motor is rated for a specific
maximum number of starts per hour or minimum
time between starts, set the MAXSTART and
TBSDLY settings accordingly. If the relay detects
MAXSTART starts within 60 minutes and the
motor stops or is tripped, the relay asserts the
TRIP output contact to prevent an additional start
until 60 minutes after the oldest start. If the motor
stops or is tripped within TBSDLY minutes of the
last start, the relay asserts the TRIP output
contact to prevent a new start until TBSDLY
minutes after the most recent start. The relay
retains accurate start time data (within
± 5 seconds) through control power cycles.
The relay will maintain the trip signal until enough
time passes that the motor can be safely
restarted. During the lockout period, the relay will
display a countdown time in minutes to the next
allowed start if a start is attempted through the
relay. The Emergency Restart function overrides
both of these limits allowing the motor to be
placed back in service in an emergency.
Settings Calculation
Setting Name =
Factory Default
MAXSTART = 3
TBSDLY = 20
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