Isolators are used to break ground loops and to measure signals with high common mode voltages.
Ground loops are created when the source of a signal and the driven instrument have their common inputs tied to the earth at each device or the common lead is used to carry AC current for some other device. AC current flowing in the common lead drops a small AC voltage due to the wire resistance. The voltage appears in series with the desired signal and creates “noise” on the desired signal. The Isolator breaks the common lead and the AC current can no longer flow.
A common mode voltage is a voltage that is connected to the + and – inputs of a device. Example – A small resistor in series with the + lead of a 138VDC battery and the – side of the battery is the “common” lead for the system. The resistor drops a small voltage proportional to the battery current. The Isolator can measure the small voltage across the resistor even though it is floating 138VDC above the system circuit common.
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Series
MM4380A |
Field Rangeable Input and Output
Span ± 16mV to ± 256VDC, ± 0.8mA to ± 100mA
Offset Cancel ±110% of Span |
MM4300 |
Factory Ranged Input and Output
Span ± 50mV to ± 250VDC, ± 1mA to ± 1ADC |
MM4300A |
Four Models, Combinations of 4/20mA and 0/10VDC Input and Output |
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UL/cUL Recognized
MM4380A and MM4300
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Series
DM4380A |
Field Rangeable Input and Output
Span ± 16mV to ± 256VDC, ± 0.8mA to ± 100mA
Offset Cancel ± 110% of Span |
DM4300A |
Four Models, Combinations of 4/20mA and 0/10VDC Input and Output |
DM4391 |
Loop Powered Isolator
4/20 mADC In and Out
Linearized ± 0.02% of Span |
UL/cUL Recognized
DM4380A and DM4300A
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DR4380A |
Field Rangeable Input and Output
Span ± 50mV to ± 256VDC, ± 1mA to ± 100mA |
DR4300 |
Factory Ranged Input and Output
Span ± 50mV to ± 250VDC, ± 1mA to ± 250mADC |
DR4302 |
Inputs: 1/5, 0/10VDC; 0/1, 4/20, 0/20, 0/50mADC
Outputs: Dual Isolated 4/20mADC
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UL/cUL Recognized
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50 mm Diameter
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SR2101 |
Isolated 2 Wire Transmitter, Head or DIN Rail Mount
Factory Ranged Input ± 16mV to ± 128 VDC, ± 0.01mA to ± 100mADC |
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