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| 型号： | PAXLCL00 |
| 厂商： | Red Lion Controls |
| 文件页数： | 6/8页 |
| 文件大小： | 0K |
| 描述： | METER CURRENT LOOP 3 1/2-DIGIT |
| 产品目录绘图： | PAX Lite Series PAX Lite Series Cut Out |
| 标准包装： | 1 |
| 系列： | PAX®LITE |
| 类型： | 过程多用表（4-20mA 回路） |
| 测量范围： | 4-20mA 回路 |
| 显示器样式： | 红色字符，黑色背景 |
| 显示器类型： | LED |
| 显示器正面尺寸： | 3.80" L x 1.95" W（96.5 x 49.5mm） |
| 显示器位数： | 3.5 |
| 显示器位数 - 高度： | 0.560"（14.22mm） |
| 背光： | 无 |
| 安装类型： | 面板安装 |
| 端子： | 端接块 |
| 电源电压： | 85 ~ 250VAC |
| 产品目录页面： | 2853 (CN2011-ZH PDF) |
| 其它名称： | RLC112 |
4.0 S CALING
THE
M ETER
PAXLCL SCHEMATIC
+V R
-V R
(+)
(-)
ADD
SUBTRACT
S1
OFFSET
DIRECTION
SWITCH
S5 S4 S3 S2
FINE
OFFSET
ADJUST
BUFFER
AMP
SPAN ADJUST
DIGITAL DISPLAY
5
-LOOP
V
I
K2
V
I
S6
2100
R
(-)
4-20MA
S7
S8
1050
525
2R
4R
mA
RANGE
S9
260
8R
(-)
4
-LOOP
CURRENT
SHUNT
RESISTORS
SPAN=150
S10
130
16R
5.5K
10-50MA
12R
RANGE
SPAN=0
FINE SPAN ADJ.
K2
V
O
A/D
VOLTMETER
S3 S2 S1
S4
CIRCUIT
(+)
DECIMAL
POINT
BACKLIGHT
ANNUNCIATOR
3
+LOOP
SWITCHES
SWITCH
can be set up over a very wide span range by
located at the back cover. The coarse span
+1500
ON
switches add parallel input resistors to the
(S7
10
8 ON
summing amplifier (K2), thereby increasing
SP
525 (S
SPAN
resistors are added. Effectively, adding more
Loop Meter has provisions for offsetting
the transfer curve over a wide range.
Essentially, offset moves the transfer
with the numerical readout axis, but it
-500
INPUT SIGNAL SCALING CIRCUIT
DESCRIPTION OF OPERATION
The PAX Lite Current Loop Meter consists of a digital volt meter combined
with an analog scaling circuit (shown above). The unit was designed primarily for
use with 4-20 mA and 10-50 mA current loop signal circuits. However, it can also
be adapted to other current ranges, such as 0-50 mA, 0-20 mA, 0-10 mA, and in
a great many applications it can be used even with 0-5 mA and 1-5 mA current
loops. In addition, input current can be reversed in polarity resulting in negative
numerical readout with a minus (-) sign displayed. Input terminals 3 and 4 are
connected in series with 10-50 mA current loops, and Terminal 3 and 5 are series
connected with 4-20 mA loops. In either case, the voltage drop generated across
the shunt resistor(s) ranges from approximately 0.12 V min. (@ 4 or 10 mA) to
0.59 V max. (@ 20 or 50 mA). The buffer amplifier (K1) conditions and filters
the input signal voltage and applies it to the input of the scaling circuit. The
procedure for scaling PAX Lite Current Loop Meters is simplified by dividing the
scaling process into two separate components, span adjustments and offset
adjustments which are defined in the following discussion.
SPAN ADJUSTMENTS
Span is defined as the numerical range that the display traverses, disregarding
decimal points, when the input signal current is varied from minimum (4 or 10
mA) to maximum (20 or 50 mA). For example, if a unit is to display 25.0 @ 4
mA and 100.0 @ 20 mA, the span is 750 (the difference between 250 and 1000).
Had the minimum display been -25.0 @ 4 mA and +100.0 @ 20 mA, the span
would be 1250 (1000 - (-250) = 1250). (Note: the terms “GAIN”, “SCALE”, and
“SENSITIVITY” are also frequently used interchangeably with the term
“SPAN.”) The PAX Lite Current Loop Meter
Span Adjustment
means of the coarse DIP switches S6-S10,
+1999
and the fine screwdriver adjustment pot,
)
+1000 50
AN )
+500
its gain, or sensitivity, as more summing
0
4 8 12 16 20
parallel input resistors, increases the slope of -500 INPUT SIGNAL CURRENT
the transfer curve (at right) and increases the
numerical readout for a given input signal
current change. The input summing resistor values are weighted in a binary
progression, so they can be switched in combinations to give 32 discrete steps of
span. The fine adjust control brackets these coarse steps and can be adjusted to the
exact span needed.
6
DIGITAL VOLTMETER
The approximate span contributed by each switch is shown on the rear label.
These values are based on the standard current-loop spans of 4 to 20 mA (16 mA
current variation) and 10-50 mA (40 mA current variation). In other words, if S7
only is turned “ON”, the numerical readout will display a change approximately
1050 for a current swing of 16 mA (4-20 mA input) or 40 mA (10-50 mA input).
If S8 were also turned “ON”, the numerical readout would swing approximately
1575 (1050 for S7 + 525 for S8) for the same signal current variation. The fine
control has a continuous span range of approximately 0-150.
OFFSET ADJUSTMENTS
In the foregoing discussion of span, the transfer curves were shown as
“ZERO-BASED”, i.e., the numerical readout displays “0” when the signal
current goes to zero. With current loop ranges such as 0-5 or 0-10, or 0-20 mA,
and with Bi-Polar (+/-) signals, this is often the desired condition. However,
with 4-20 and 10-50 mA current loops, the minimum current level of 4 or 10
mA usually represents the zero level of the parameter being displayed. There are
also many applications where the
minimum (or zero level) represents some Offset Adjustment
value that does not fall on a zero based
transfer curve. To accommodate non-zero
+1999
based applications, the PAX Lite Current
+1500
+1000
+500
curve up or down to change its intercept 0
4 8 12 16 20
INPUT SIGNAL CURRENT
does not change the slope (SPAN) of the
transfer curve. In the PAX Lite Current
Loop Meter, offset is accomplished by
adding (or subtracting) a constant at the input of the summing amplifier (K2).
This offset constant is summed in with a switched binary resistor network and
a fine adjust offset control in a similar manner to that used for span adjustment.
Switches S2-S5 can be turned on in combinations to give 16 different coarse
offset levels. Each switch is labeled to show the approximate amount of offset
contributed when it is turned “ON”. Switch 1 selects the polarity of the
switched-in offset value and allows offsetting the transfer curve “UP” (adding
the offset constant) or “DOWN” (subtracting). The fine offset control has a
numerical readout range of ±100 and brackets all the coarse switched ranges.
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相关代理商/技术参数 |
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| PAXLCR00 | 制造商:Red Lion Controls 功能描述:Counter; Rate Meter; LCD; 6 Digit, 50-250VDC 制造商:Red Lion Controls 功能描述:COUNT/RATE METER |
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| PAXLIA00 | 功能描述:METER AC CURRENT 3 1/2-DIGIT RoHS:是 类别:工业控制，仪表 >> 仪表 - 面板，数字 系列:PAX®LITE 标准包装:12 系列:* 其它名称:Q7072030 |
| PAXLID00 | 功能描述:METER DC CURRENT 3 1/2-DIGIT RoHS:是 类别:工业控制，仪表 >> 仪表 - 面板，数字 系列:PAX®LITE 标准包装:12 系列:* 其它名称:Q7072030 |
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