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QLS Quad Output 4-20 mA
Current
Loop
Splitter / Retransmitter
Splits 1 input signal into
4 independent 4-20 mA current loops
with ± 10V common mode isolation between input & outputs.
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Description
Problems with Devices in Series
In many industrial applications, the
same 4-20 mA signal from a transmitter is sent to multiple devices in series,
such as panel meters, recorders and PLCs. This can cause a number of
problems:
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1. |
All
devices in the loop cannot share a common ground, but must be
electrically floating. This is often not possible. |
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2. |
When any device in a loop is
removed, fails or if a wiring fault occurs, all other devices in
the loop loose their 4-20 mA signal. |
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3. |
The
transmitter voltage compliance limit may be exceeded, since the
voltage drops across loads in series are additive. |
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4. |
The 4-20 mA signal to each load
device cannot be individually adjusted for calibration purposes. |
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Not so good: A single 4-20 mA
loop from a sensor to panel meters,
a recorder and a PLC. If the loop opens, all devices in the loop
fail. |
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Much better: Four independent
4-20 mA loops with
± 10V
common mode
isolation. If any of the output loops opens, only a single
device is affected.
The output loops can share a common ground |
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The Loop Splitter
/ Retransmitter Solution
Model QLS Quad Output Loop Splitter / Retransmitter solves the problems by
sourcing up to four (4) independently adjustable 4-20 mA outputs from a single input.
The outputs can share a common ground. The input and outputs are mutually isolated to ±10V by means
of active circuitry to accommodate differences
in local grounds with normal industrial grounding practices. If any device
in an output loop is removed from a loop or fails, or if a wiring fault
occurs, the other loops continue to operate properly.
Each loop only drives a single load, avoiding compliance problems. The input to the
quad loop splitter can be 4-20 mA, 1-5V, 0-5V or 0-10V, as selected by jumpers. Power for the loop splitter can
be 85-264 Vac (Model QLS-1) or low voltage 10-48 Vdc or 12-32 Vac (Model
QLS-2). An excitation output is provided on the signal input side to a drive
a 2- or 3-wire transmitter at 24 Vdc and up to 30 mA. Each output loop provides two
potentiometers for ±10% fine adjustment of zero and span, a yellow LED lamp to indicate loop continuity,
and a test point across a 10Ω series resistor, where 200 mV corresponds to
20 mA. This allows a multimeter to be used to measure the loop current
without breaking the loop. |
Specifications
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Signal
Input |
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Signal Type
Input Resistance
Transmitter
Excitation |
4-20 mA,
1-5V, 0-5V, 0-10V (jumper selectable)
50 ohms for 4-20 mA, 500 kΩ for 1-5V &
0-5V, 1 MΩ for 0-10V
24 Vdc nominal, 30 mA max |
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Signal Outputs |
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Number of
Outputs
Signal Type
Zero & Span Adjustment
Signal Isolation
Voltage Compliance
Load Regulation
Accuracy
Span Tempco
AC Rejection
Response Speed
Loop Current Sense
Loop Continuity Indication |
4
4-20 mA
± 10% for each output with 25-turn potentiometers
± 10V active isolation between input & outputs
12V (600 ohms per loop at 20 mA)
± 0.005% of span from 0Ω to 600Ω
± 0.02% max pan error at 23°C
± 10 ppm/ºC (0.16 μA/ºC) typical, ± 25 ppm/ºC (0.4 μA/ºC) max
90 dB from DC to 60 Hz
2 ms risetime, 7 ms settling time to 0.1% of final value
10Ω ± 0.5% series resistor so that 200 mV = 20 mA
Yellow LED lamp per loop, brightness proportional to current. |
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Power Input |
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Standard Power (QLS-1)
Low Power Option (QLS-2)
Power Frequency
Power Isolation
Power Consumption
Power On Indication |
85-264 Vac or 90-300 Vdc (DC operation not UL approved)
10-48 Vdc or 12-32 Vac
DC or 47-63 Hz
250V rms working, 2.3 kV rms per 1 min test
3.5 W max, all loops delivering 20 mA
Green LED lamp |
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Mechanical |
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Mounting
Dimensions
Weight
Connectors
Wire Size |
35 mm DIN Rail
per
EN50 022
22.5 x 103 x 128 mm (0.9" x 4.1" x 5.0") W x H x D
140 g (5 oz)
Detachable plug-in screw-clamp connectors
28-12 AWG, 2.5 sq. mm max |
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Environmental |
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Operating Temperature
Storage Temperature
Relative Humidity
Cooling Required |
-40°C
to 70°C
-40°C to 85°C
95% at 40°C, non-condensing
Mount units with ventilation holes at top and bottom.
Leave 6 mm (1/4") between units, or force air with a fan. |
Pinouts & Field Wiring
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Floating
loads: Any output load R that is
floating (not connected to a local ground or
earth ground) can be connected between
current output (Pin 1) and current return
(Pin 2). Current return is internally tied
to signal ground SG, which can be floating
or be connected to earth ground. |
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Grounded
loads: Any output load R can be
connected to a local loop ground LG instead
of current return. The loop grounds LG can
each be different, but can only differ from
signal ground SG by a common mode voltage
CMV, which is defined as VLG - VSG. Signal
ground SG must be tied to earth ground EG or
be within 1 Volt of EG. |
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Input-output
isolation: If a load R is grounded to a
local loop ground LG, the available common
mode voltage CMV is limited on the positive
side by the unit’s internal power supply and
on the negative side by the 600 mW power
dissipation limit of an output transistor.
The diagram to the right shows allowable CMV
as a function of output load resistance R.
For example, with a 250 ohm load, CMV can
range from -13V to +17V. With a 500 ohm
load, CMV can range from -18V to +12V. The
unit will not work correctly if CMV limits
are exceed or load resistance is greater
than 600 ohms. |
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Ordering
Guide
Model QLS Quad Output 4-20 mA Loop Splitter
/ Retransmitter
Click on the radio buttons to build a model number with pricing (shown below the Ordering Guide).
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