Model 1620A Transconductance Amplifier
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Product Summary
The BLI 1620A Transconductance Amplifier is designed to provide calibration and test
departments a highly accurate, highly precise, high current calibration source.
The 1620A provides high accuracy current levels from dc to over 10 kHz for calibrating
ammeters, current transformers and shunts. It also provides output current up to 100
Amperes. and as such may also be used as a high accuracy power supply, and as a power
source in welding and bonding applications.
The 1620A converts a signal voltage applied to its input, into a high resolution output
current whose value is directly proportional to the input signal level. As a example, if
an input of 2 Volts is applied on the 20 Ampere range, a current of 20 Amperes will be
produced at he output terminals. With dc input voltages, the output current provides the
same polarity as the driving signal, and with ac inputs the output will faithfully
reproduce the frequency, phase, waveshape, symmetry and dc offset of the input source. A
wide range of currents can be produced with seven switchable ranges from 200 microamperes
to 100 Amperes rated for positive or negative dc and ac sinusoidal rms at crest factor to
1.45 maximum. Signal inputs can be up to 100 Volts above or below the earth grounded
enclosure.
The 1620A can be driven by commercially available manual or programmable, precision ac
or dc voltage calibrators and sources, and when equipped with the IEEE-488 option a fully
automated current calibration system can be configured to optimize throughput in
calibration procedures.
Definitions:
Transconductance Amplifier:
An amplifier, or voltage-to-current converter, that supplies an output current
proportional to its input voltage. Source impedance of the amplifier is much greater than
the impedance of the output load and the device has the characteristics of constant
current source until its "Compliance Voltage" is exceeded.
Siemens:
The unit of transconductance that is described by the ratio of voltage input to
current output of a voltage-to-current converter, or transconductance amplifier.
Siemens = Amperes/Volts
Compliance Voltage:
Compliance Voltage is the output voltage produced by a transconductance amplifier as it
delivers a given constant current over a range of load resistance. Compliance voltage is
calculated as the product of load impedance and current out. The amplifier will sustain
the desired current until the Compliance Voltage rating is exceeded..
Product Features
Product Specifications
AC Mode
Ranges:
0 to 100A rms, at 100 Siemens
0 to 20A rms, at 10 Siemens
0 to 2A rms, at 1 Siemens
0 to 200mA rms, at 100 milliSiemens
0 to 20mA rms, at 10 milliSiemens
0 to 2mA rms, at 1 milliSiemens
0 to 200mA rms, at 100 microSiemens
Ratio of Input Voltage to Output Current:
All ranges: 2 Volts input for full range current output,
except 100A range which is 1 Volt for 100A rms output current. AC rms is rated for
sinusoidal inputs with a maximum crest factor of 1.45 at full range current output, and
greater than 3 at midrange.
Resolution: (Referred to input voltage)
1mA on the 200mA range.
±0.01% of range on the 2mA to 20A ranges.
Compliance Voltage:
100A range: ³ 3
Volts rms (±4.2 Volts peak)
20A range: ³ 4
Volts rms (±5.6 Volts peak)
:All other ranges: ³ 5.5 Volts rms (±7.7 Volts peak)
Open Circuit Compliance Voltage:
Not greater than ±15 Volts peak.
Accuracy of Output Current:
Allowable deviation of range output current input voltage:
±(0.15% of output current +0.1% of range) to 1 kHz.
Bandwidth (Sinusoidal input):
100A range: DC to 20 Hz to 100 Amps peak
20 Hz to 1 kHz to 100 Amps rms
20A range: DC to 1 kHz
2A range DC to 5 kHz
All other ranges: DC to > 10 kHz
Load Regulation/Transient Recovery Rime:
Output Current settles within ±0.01% of initial value in £ 5 seconds with any change in load.
Total Harmonic Distortion:
< 0.1% of the fundamental at 100A rms and 1 kHz sinewave.
Load Requirements: The current output will supply
resistive and capacitive loads as well as inductive loads to 2 millihenries at full
specified currents and frequencies which permit operation within the rated compliance
voltage.
DC Mode
Ranges and Transconductance:
0 to ± 100A at 100 Siemens
0 to ± 20A at 10 Siemens
0 to ± 2A at 1 Siemens
0 to ± 200mA at 100 milliSiemens
0 to ± 20 mA at 10 milliSiemens
0 to ± 2 mA at 1 milliSiemens
0 to ± 200mA at 100 microSiemens
Ratio of Input Voltage to Output Current:
All ranges ±2 Volts input for ± full range current output; except 100A range which is ±
1 Volt for ± 100A output current.
Resolution: (Referred to input voltage)
1mA on the ± 200mA range.
0.01% of range from ±2mA to ±20A ranges.
Compliance Voltage: ± 4 Volts minimum on the ± 20A
and ±100A ranges. ±7.5 volts minimum on all other ranges.
Open Circuit Compliance Voltage:
Not greater than ±15 Volts peak.
Accuracy of Output Current:
Provides accuracy of ± (0.02% of output current +0.02% of range) on all the ranges.
Load Regulation: to ±10%; 50 to 400 Hz
Transient Recovery Time: Output current settles within ± 0.01% of initial value in £ 5
seconds with any change in load.
General
Input Terminals and Impedance: Gold plated universal
binding posts. 10 Megohm input resistance.
Output Terminals: Gold plated, universal binding
posts on all ranges except 100A range which uses Superior Model RS 100G high current
female terminals.
Rear Input: Front or rear input selectable by front
panel switch.
Off ground Operation: Instrument is capable of
operating input LO and output LO to ±100V dc with respect to case ground input. LO to
case resistance: 0.5 Megohm
Isolation: Input voltage LO may be separated by ±10
volts common mode voltage with respect to output current HI and LO terminals.
Environmental Characteristics:
Designed to comply with MIL-T-28800, Class 5.
Temperature:
Storage: -40 to +75o
C
Operation: 0 to 50o
C
Humidity:
Full Accuracy: 20% to 80% RH to 40 o C
Usable: 10% to 100% RH without condensation
Altitude:
Storage: 0 to 15 Km (50,000 ft.)
Operating: 0 to 3 Km (10, 000 ft.)
Controls and Indicators:
ON-OFF Power Switch
FRONT/REAR Input Switch - Selects front or rear panel input voltage terminals
RANGE - 6 push-button switches select one of seven ranges.
OVERCOMPLIANCE Indicator - Lights when load compliance voltage is exceeded.
INPUT OVERDRIVE Indicator - Lights when input drive voltages are exceeded.
OPERATE/STANDBY Switch - Disables output current drive.
REMOTE Indicator - Lights when remote operation is selected.
Protection:
Input Protection: to 200 Vrms.
Output Protection: Open circuit or short circuit protection and output compliance voltage
limited to ±15 volts peak across current output terminals.
Sensitive components protected by high temperature cut out with auto reset and
"standby" indicator.
Ventilation: Forced air ventilation is provided whenever interior temperature rises above
50 Degrees Celsius.
Size:
Height: 267 mm (10 1/2")
Width: 19" standard EIA rack mount configuration
Depth: 416 mm (16 3/4") behind panel, 457 mm (18") overall
Weight: 50 kg (80 lbs.)
64 kg (110 lbs.) shipping
Power Requirements: 100V or 120V or 220V or 240V
±10%. Single phase, 50 to 60 Hz 2 KVA. Fully protected with 20A magnetic circuit breaker.
