GE 239, Instruction Manual

Page: 85 / 158

GE Multilin 239 Motor Protection Relay 5-5
5 MONITORING 5 MONITORING
5
The current resolution is 0.1 A if the
&735,0$5<
setting is
≤
50 A. The resolution is 1A if the
&7
35,0$5<
setting is > 50A.
• GROUND CURRENT: If excessive ground current was present at the time of trip, an insulation
failure is likely. With the motor off-line, check the insulation resistance in all three phases and
cable wiring.
• CURRENT UNBALANCE: Excessive unbalance can be caused by loose terminal connections,
faulty utility supply, a blown fuse, or faulty contactor. Check for these before restarting the motor.
• STATOR (BEARING) RTD 1-3 (OPTION): If any stator RTDs shows a high temperature, check
that the ventilation to the motor is clear. Repeated starting using the Emergency Restart feature
will cause the motor to overheat and should be avoided. After an overload trip, the RTD tempera-
ture may be elevated. Verify that the motor has cooled before restarting by checking each RTD
temperature using the messages
$0(7(5,1*?7(03(5$785(
. If the RTD is installed on a bearing,
an excessive bearing temperature usually indicates a need for lubrication or a fault with the bear-
ing itself. Lubricate the bearing then monitor its temperature closely after starting the motor.
• SETPOINTS GROUP IN USE: Alternate setpoints (i.e.
3+$6( &7 35,0$5<
,
)8// /2$' &855(17
,
etc.) can be selected using the Option Switch 1 and Option Switch 2 inputs as explained in Sec-
tion 4.7: SWITCH INPUTS on page 4–33. One of four possible groups of setpoints can be
selected at once. This message displays the selected group at the time of the last trip.
• 2nd (3-5) LAST TRIP: A trip record of the last 5 causes of trip is retained for diagnosing persis-
tent problems. Each new trip is added to the trip record and the oldest (fifth) cause of trip is
erased. No trip data is saved in this trip record. However, by observing repeated trips of the same
type, an indication of an inherent fault is obtained for maintenance purposes.
c) MOTOR STATISTICS
The total motor running time (including start conditions) and the maximum average current present
during the last successful start are monitored here.
d) SWITCH STATUS
To assist in troubleshooting, the state of each switch can be verified using these messages. A sepa-
rate message displays the status of each input identified by the corresponding name as shown in
Figure 2–3: TYPICAL WIRING DIAGRAM on page 2–4. For a dry contact closure across the corre-
sponding switch terminals the message will read closed.
NOTE: If the switch simulation is turned on in
67(67,1*?6:,7&+ 6,08/$7,21?6,08/$7,21
, the status
shown in these messages will be of the simulated inputs.
• SETPOINTS GROUP CURRENTLY IN USE: Alternate setpoints (i.e.
3+$6( &7 35,0$5<
,
)8//
/2$'&855(17
, etc.) can be selected using the Option Switch 1 and Option Switch 2 inputs as
explained in Section 4.7: SWITCH INPUTS on page 4–33. One of four possible groups of set-
points can be selected at once. This message displays the currently selected group.
e) PROGRAMMABLE MESSAGE
A 40 character message can be programmed using the keypad or via the serial port using the 239PC
software. See 4.2: S1: 239 SETUP on page 4–3 for an example of programming this message using
the keypad.
This message can be used for identification purposes such as company name, site name, station
name, relay identification number, etc. It can be chosen as the default message so it is displayed
when the unit is left alone.