Rtd Sensor Connections - GE 469 Instruction Manual

2 INSTALLATION
a) DESCRIPTION
The 469 monitors up to 12 RTD inputs for Stator, Bearing, Ambient, or Other temperature monitoring. The type of each
RTD is field programmable as 100 Ω Platinum (DIN 43760), 100 Ω Nickel, 120 Ω Nickel, or 10 Ω Copper. RTDs must be
three wire type. Every two RTDs shares a common return.
The RTD circuitry compensates for lead resistance, provided that each of the three leads is the same length. Lead resis-
tance should not exceed 25 Ω per lead for platinum/nickel RTDs or 3 Ω per lead for copper RTDs. Shielded cable should be
used to prevent noise pickup in the industrial environment. RTD cables should be kept close to grounded metal casings
and away from areas of high electromagnetic or radio interference. RTD leads should not be run adjacent to or in the same
conduit as high current carrying wires.
469
RELAY
CHASSIS
GROUND
SHIELD
HOT
COMPENSATION
RETURN
IMPORTANT: The RTD circuitry is isolated as a group with the Analog Input circuitry and the Analog Output
circuitry. Only one ground reference should be used for the three circuits. Transorbs limit this isolation to
NOTE
±36 V with respect to the 469 safety ground.
b) REDUCED RTD LEAD NUMBER APPLICATION
The 469 requires three leads to be brought back from each RTD: Hot, Return and Compensation. This can be quite expen-
sive. It is however possible to reduce the number of leads required to 3 for the first RTD and 1 for each successive RTD.
Refer to the figure below for wiring configuration for this application.
The Hot line would have to be run as usual for each RTD. The Compensation and Return leads, however, need only be run
for the first RTD. At the motor RTD terminal box, the RTD Return leads must be jumpered together with as short as possi-
ble jumpers. The Compensation leads must be jumpered together at the 469.
GE Multilin
Courtesy of NationalSwitchgear.com
MOTOR
STARTER
B1
A1
A2
A3
RTD
TERMINALS
IN MOTOR
STARTER
Figure 2–18: RTD WIRING
469
L1
Hot A1
L2
Compensation
A2
L3
RTD Return A3
J1
L4
Compensation
A4
L5
Hot
A5
J2
L6
Hot
A6
L7
Compensation
A7
RTD Return
A8
No connection
Figure 2–19: REDUCED WIRING RTDS
469 Motor Management Relay

2.2.8 RTD SENSOR CONNECTIONS

3 WIRE SHIELDED CABLE
Route cable in separate conduit from
current carrying conductors
RTD TERMINALS
AT MOTOR
Maximum total lead resistance
25 ohms (Platinum & Nickel RTDs)
3 ohms (Copper RTDs)
Motor Control
Motor
Terminal Box
+
RTD1
–
J3
+
RTD2
–
J4
+
RTD3
–
808722A1.CDR
2.2 ELECTRICAL
2
MOTOR
RTD IN
MOTOR
STATOR
OR
BEARING
806819A5.CDR
2-15