Other Rtd Setpoints; Overload Curve Setpoints; Figure 3.4 Standard Overload Curves With Overload Pickup - GE MULTILIN 269 MOTOR MANAGEMENT RELAY Series Instruction Manual

RTD3 will be used for motor temperature calculations.
Thus, in this case, RTD4, RTD5, and RTD6 may be
used for any other RTD temperature monitoring func-
tion desired.
If a stator RTD becomes open circuited during use, the
ACTUAL VALUES display for that RTD will be "no
RTD". Readings from the disconnected RTD will then
be ignored. The 269 Plus relay will enter TRIP/ALARM
mode to warn the user of the faulty RTD if the "No Sen-
sor Alarm" is enabled (SETPOINTS, page 5). Similarly,
if the "Low Temperature Alarm" is enabled (Setpoints,
page 5) the relay will enter Trip/Alarm mode to warn the
user of any one RTD measuring 0°C (32°F). This set-
point can be used to detect shorted RTDs given that the
normal running temperature of the motor's stator,
bearing and other RTDs is not 0°C or less. After a sta-
tor RTD temperature trip, alarm, or high alarm setpoint
is exceeded the 269 Plus relay will not allow the active
output relays to be reset until the temperature has
fallen 4°C below the exceeded setpoint.

3.17 Other RTD Setpoints

A total of 8 RTD inputs is provided on the 269. Any
RTD inputs not used for stator RTD protection can be
used for other temperature monitoring functions.
These will commonly be used for motor and load bear-
ings. Separate alarm and trip level temperatures can
be selected for each RTD in SETPOINTS mode, page
2.
Trip and alarm level setpoints should be set to "OFF"
for any unused RTD terminals. When no connection is
made to a set of RTD terminals or if a sensor becomes
damaged, the ACTUAL VALUES display for that RTD
will be "no RTD". If the "No Sensor Alarm" is enabled
(SETPOINTS, page 5) the relay will enter TRIP/ALARM
mode to warn the user of any open RTD connection
that does not have its trip and alarm level setpoints
stored as "OFF". Similarly, if the "Low Temperature
Alarm" is enabled (Setpoints, page 5) the relay will
enter Trip/Alarm mode to warn the user of any one RTD
measuring 0°C (32°F).
shorted RTD's in motors where the normal running
temperature, hence stator RTD and bearing RTD tem-
perature, is not 0°C (32°F) or less. If an RTD becomes
shorted, and the "Low Temperature Alarm" setpoint is
enabled, the 269 will detect that shorted RTD, and dis-
plays a message indicating a "Low Temperature Alarm"
for that specific RTD. The RTD number is also dis-
played for ease of troubleshooting. This feature is not
recommended to be used in harsh environments where
normal running motor temperature (stator and bearing
RTD temperature) can go to 0°C or less.
RTDs connected to the RTD terminals of the 269 relay
must all be of the same type. After an RTD tempera-
ture trip or alarm setpoint is exceeded, the 269 relay
will not allow the activated output relays to be reset
The 269 can detect
until the temperature has fallen 4 C below the exceeded
setpoint.
To use RTD #8 for ambient air temperature sensing a
setpoint in page 5 of SETPOINTS mode must be
changed (see sections 3.4, 3.20).

3.18 Overload Curve Setpoints

The overload curve is chosen in SETPOINTS mode,
page 3. The curve will come into effect when the motor
phas current goes over the Overload Pickup level x
FLC (see Figure 3.4). When this is true the motor
thermal capacity will be decreased accordingly;
output relay assigned to the OVERLOAD TRIP function
will activate when 100% of the available thermal ca-
pacity has been exhausted. Thermal capacity may be
reduced by the presence of unbalance and RTD bias as
well as overload (if the U/B and RTD inputs to thermal
memory are enabled). Thus the times on the overload
curve may be reduced due to phase current unbalance
(see section 3.20). A choice of eight standard curves,
as shown in Figure 3.5, is available on the 269.
Figure 3.4 Standard Overload Curves with Overload
Pickup
3 SETUP AND USE
the
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