GE 239 Instruction Manual page 33

CHAPTER 2: INSTALLATION
SELECTED OUTPUT
Average Phase Current
Motor Full Load %
Thermal Capacity
RTD 1-3 Temperature
Forced Output
* 1 Amp CT secondary = 1 A, 5 Amp CT secondary = 5 A
239 MOTOR PROTECTION RELAY – INSTRUCTION MANUAL
Courtesy of NationalSwitchgear.com
. Use the TYPE message to select one of the following for output: phase CT
TYPE & RANGE
(secondary) amps, % motor full load current (FLC), thermal capacity used (100% = motor
tripped), RTD1 temperature, RTD2 temperature, or RTD3 temperature. The RANGE message
selects the output current as: 0-1 mA, 0-20 mA or 4-20 mA. Range assignment is shown
below in Table 2–4: Analog Output Range Assignment.
Table 2–4: Analog Output Range Assignment
0-1 mA
0 mA
0 A
0%
0%
0°C
0%
This output is a current source suitable for connection to a remote meter, chart recorder,
programmable controller, or computer load. Use the 4-20 mA with a programmable
controller that has a current input. If only a voltage input is available use a scaling resistor
at the PLC terminals to scale the current to the equivalent voltage and select the 0 to 20
mA output. For example, install a 500 Ω resistor across the terminals of a 0 to 10 V input to
make the 0 to 20 mA output correspond to 0 to 10V (R = V/I = 10 V / 0.02 A = 500 Ω). When
the GE Multilin TCS2 thermal capacity meter is connected to the terminals, select the 0 to 1
mA range. Current levels are not affected by the total lead and load resistance which must
not exceed 600 Ω for 0-20 mA and 4-20mA range and 2400 Ω for 0-1mA range. For
readings greater than full scale the output will saturate at 21 mA (0-20/4-20 range) or 1.1
mA (0-1 range). This analog output is isolated. Since both output terminals 18 and 19 are
floating, the connection of the analog output to a process input will not introduce a ground
loop. Part of the system should be grounded for safety, typically at the programmable
controller. For floating loads, such as a meter, ground terminal 19 externally. Terminal 20 is
internally grounded and may be used as a shield ground if required. Ground the shield at
one end only to prevent ground loop noise.
SERIAL PORT (15/16/17)
A serial port provides communication capabilities between the 239 and a remote
computer, PLC or distributed control system (DCS). Up to thirty-two 239 relays can be daisy
chained together with 24 AWG stranded, shielded, twisted pair wire on a single
communication channel. Suitable wire should have a characteristic impedance of 120 Ω
such as Belden #9841. These wires should be routed away from high power AC lines and
other sources of electrical noise. The total length of the communications wiring should not
exceed 4000 feet for reliable operation. Correct polarity is essential for the
communications port to operate. Terminal 15 (485 A+) of every 239 in a serial
communication link must be connected together. Similarly, terminal 16 (485 B-) of every
239 must also be connected together. These polarities are specified for a 0 logic and
PROGRAMMED RANGE
0-20 mA
1 mA 0 mA 20 mA
1A/5A* 0 A 1A/5A*
200% 0% 200%
100% 0% 100%
180°C 0°C 180°C
100% 0% 100%
4-20 mA
4 mA 20 mA
0A 1A/5A*
0% 200%
0% 100%
0°C 180°C
0% 100%
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