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THERMOMETRY BRIDGE METROLOGY STANDARD |
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F700
Precision Thermometry Bridge Secondary
Standard. Accuracy < +/- 0.5 ppm.
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The Model F700 Thermometry Bridge Standard is a high accuracy resistance
bridge designed specifically for resistance thermometry.
Its unique AC
bridge circuitry eliminates thermal EMF effects to provide you with fast,
reliable measurements under a wide range of real operating conditions.
F700 Thermometry Bridge a special input guard circuit maintains accuracy by minimizing the effect of
probe or cable leakage to ground.
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The effect of
cable and probe reactance is
eliminated by an on-board quadrature servo
allowing you typically to make measurements
up to 100 meters from the PRT.
The differential capability allows the resistance
of one PRT to be measured against another
directly and provides the most accurate
comparison calibration technique.
The F700 can
be used with one or more
switchboxes for multi channel calibration. |
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Features |
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Digital display |
Rt/Rs digital display; 0.000 000 to
3.999 999 |
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Balance |
Automatic or manual balance |
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Thermometer mA |
Selectable: 01, 0.2, 0.5, 1, 2, 5,
10mA, plus root 2 for all values |
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Bandwidth |
Selectable: 0.1, 1 or 10 Hz for the
analogue meter |
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Check |
Unity & zero self test confirms
accuracy of the 1:1000000 ratio and 0.000000 settings |
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Sensitivity |
Selects gain for manual bridge
balance |
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Meter |
Normal: |
Indicates the balance status of the
bridge |
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Quadrature: |
Shows the reactive component of PRT,
lead and Rs resistor (if present). Automatically cancelled with
on board servo. |
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Residual: |
Indicates noise and interference
from external sources |
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Rs Trim |
Allows the internal Rs to be trimmed
to precisely 100 ohms against an external standard. |
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Ext / Int Rs |
Selects either internal 100 ohm
reference resistor in a temperature controlled oven at 36ºC, or
any external reference between 1 ohm and 1000 ohms |
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Lead connections |
True four wire connections for
resistance thermometer (Rt) and standard resistor (Rs).
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Balance meter |
Shows bridge balance, quadrature or
residual noise, as selected by (7) |
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LED Indicators |
On-Line: |
Indicates when the F700 is active, or "on-line" with a computer |
| Oven: |
Illuminates if the internal Rs resistor oven is not at the
preset temperature |
| Residual
(overload): |
Indicates that very high levels of noise or interference are
present |
| Quad: |
Indicates very high levels of quadrature, or reactance, from the
cables |
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Ratio Rt/Rs |
Rt/Rs decade switch; 7 decades of
switches to balance the F700 manually |
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Specification |
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Accuracy |
F700A: |
<±1ppm
of reading or 1 digit, whichever is the greater.
Equivalent to 0.25mK @ unity ratio (0.01ºC) or 1mK over the full
range |
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F700B: |
<±0.5ppm
of reading or 1 digit, whichever is the greater.
Equivalent to 0.25mK @ unity ratio (0.01ºC) or 0.5mK over the
full range |
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Temperature equivalents for 25.5ohm SPRT against a 25ohm
standard @ 1mA |
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F700A: |
<±5ppm @
unity ratio, equivalent to 6mK up to 1064ºC |
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F700B: |
<±2.5ppm
@ unity ratio, equivalent to 3mK up to 1064ºC |
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Temperature equivalents for 0.25ohm HTSPRT against a 1ohm
standard @ 10mA |
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Resolution |
1 least significant digit |
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Linearity |
<±1 least significant digit |
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Measurement time |
10 second for full balance |
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Warm up time |
<30 seconds with external standard,
<5 minutes with internal standard |
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Thermometers |
R0.01 of 1000ohm, 100ohm,25ohm,
10ohm, 1ohm, 0.25ohm and any intermediate value |
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External standard resistor range |
1ohm to 1000ohm AC/DC resistance |
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Internal Standard Resistor |
100 ohm ±50ppm, with t/c of
<0.3ppm/°C, in a temperature controlled oven at 36°C. A trim
control allows calibration against an external standard. |
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Measurement Range |
0-3.999999 ratio of two resistors;
0-3.999999 ohms where Rs = 1 ohm |
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0-399.9999 ohms where Rs = 100 ohms;
0-1500.000 ohms where Rs = 1000 ohms. |
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Sensor current |
0.1, 0.2, 0.5, 1 ,2, 5, or 10mA plus
root2 multiplier. Constant current, stabilized to ±1% of nominal
value. |
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Communications |
RS232 |
300 baud, 8 bits, no parity and 2
stop bits |
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IEEE-488 |
Address selectable from 0 to 15 |
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Analogue outputs |
±10V null balance signal, unfiltered
P.S.D output |
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±10V null balance signal, filtered
output (1 Hz bandwidth) |
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Operating conditions |
0°C to 30°C (32°F to 86°F), 10 to
90%RH |
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Power requirements |
240,220,120,100 VAC (±10%)
selectable on rear panel, 50 or 60 Hz, 70VA max. |
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Dimensions / weight |
520mm (W) x 155mm (H) x 466mm (D).
3U x 19" front panel. 15Kg |
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Accessories |
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| SB148 |
10 channel
auto/manual mulitplexer, with individual preset "keep warm"
current |
| SB148/01 |
As SB148, with 4
individual "keep warm" currents per channel |
| SB158 |
Driver/interface for
up to 2 x SB148 or 5B1 48/01 multiplexers (Specify RS232 or IEEE |
| SB158/01 |
Driver/interface for
up to 6 x 5B148 or SB148/01 multiplexers (Specify R5232 or IEEE) |
| F700 AS1 System |
F700 complete with
SB148 and SB158 multiplexer in cabinet (Specify F700A or F700B) |
| F700 AS2 System |
As AS1 system, but
with SB148.01 multiplexer (Specify F700A or F700B) |
| RW1, 10, 25, 100,
1000 |
"Wilkins" AC/DC
Standard Resistor. Values: 1, 10, 25,100 and 1000 ohms |
| RR1, 10, 25, 100,
1000 |
Laboratory AC/DC
Standard Resistor. Values: 1, 10, 25,100 and 1000 ohms |
| RTWE |
Thermal enclosure
for RW & RR resistors |
| FR4 |
Four oven controlled
resistors in a cabinet Choose Values: 1, 10, 25,100 and 1000
ohms |
| F/ACC |
FA1, FA2 and FA3
cable set |
| Soft700 |
ITS-90 temperature
measurement and data acquisition software |
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