Thermometry Bridges
F700 Secondary Standards Bridge
Features |
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Accuracy: <±0.5ppm
(±0.5 micro K over full range) |
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Resolution: 0.25ppm
(0.25 micro K over full range) |
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Linearity: <±1 LSD
(0.25 micro K over full range) |
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Warm up time: < 30 seconds
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F700 Brochure (PDF, approx 257KB) |
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For more information about this product contact ASL |
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The Model F700 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. A special input guard circuit maintains accuracy by minimising the effect of probe or cable leakage to ground. The effect of cable and probe reactance is eliminated by an on-board quadrature servo allowing you typically to make measurements up to 100 metres 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.
F700 Features
See the table below for a run-down of this product's features and capabilities.
Digital display |
Rt/Rs digital display; 0.000 000 to 3.999 999 |
Balance |
Automatic or manual balance |
Thermometer mA |
Selectable: 01, 0.2, 0.5, 1, 2, 5, 10mA, plus root 2 for all values |
Bandwidth |
Selectable: 0.1, 1 or 10 Hz for the analogue meter |
Check |
Unity & zero self test confirms accuracy of the 1:1000000 ratio and 0.000000 settings |
Sensitivity |
Selects gain for manual bridge balance |
Meter |
Normal: |
Indicates the balance status of the bridge |
Quadrature: |
Shows the reactive component of PRT, lead and Rs resistor (if present). Automatically cancelled with on board servo. |
Residual: |
Indicates noise and interference from external sources |
Rs Trim |
Allows the internal Rs to be trimmed to precicely 100 ohms against an external standard. |
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 |
Balance meter |
Shows bridge balance, quadrature or residual noise, as selected by (7) |
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 cables. |
Ratio Rt/Rs |
Rt/Rs decade switch; 7 decades of switches to balance the F700 manually |
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For more information about this product contact ASL
Specification
See the table below for infomation about specifications.
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 |
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 |
F700A: |
±5ppm @ unity ratio, equivalent to 6mK up to 1064ºC |
F700B: |
Temperature equivalents for 0.25ohm HTSPRT against a 1ohm standard @ 10mA |
Resolution |
1 least significant digit |
Linearity |
<±1 least significant digit |
Measurement time |
10 second for full balance |
Warm up time |
<30 seconds with external standard, <5 minutes with internal standard |
Thermometers |
R0.01 of 1000ohm, 100ohm,25ohm, 10ohm, 1ohm, 0.25ohm and any intermediate value |
External standard resistor range |
1ohm to 1000ohm AC/DC resistance |
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 |
Measurement Range |
0-3.999999 ratio of two resuistors; 0-3.999999 ohms where Rs = 1 ohm |
0-399.9999 ohms where Rs = 100 ohms; 0-1500.000 ohms where Rs = 1000 ohms |
Sensor current |
0.1, 0.2, 0.5, 1 ,2, 5, or 10mA plus root 2 multiplier. Constant current, stabilised to ±1% of nominal value |
Communications |
RS232 |
300 baud, 8 bits, no parity and 2 stop bits |
IEEE-488 |
Address selectable from 0 to 15 |
Analogue outputs |
±10V null balance signal, unfiltered P.S.D output |
±10V null balance signal, filtered output (1 Hz bandwidth) |
Operating conditions |
0°C to 30°C (32°F to 86°F), 10 to 90%RH |
Power requirements |
240,220,120,100 VAC (±10%) selectable on rear panel, 50 or 60 Hz, 70VA max |
Dimensions / weight |
520mm (W) x 155mm (H) x 466mm (D). 3U x 19" front panel. 15Kg |
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For more information about this product contact ASL
Accessories
The following accessories are available for use with the F700.
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 |
RWTE1 |
Thermal enclosure for 1 off RW resistor |
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 |
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For more information about the above accessories contact ASL
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