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interference factors should be guaranteed, so as to ensure accurate calibration
results.
(1) Selection of standard device: Four-wire real material object resistance (i.e.
ZX74) should be adopted for RTD, and no simulated resistance can be used; the
internal resistance of the thermocouples signal source should be less than 100Ω.
Constant temperature oven (or ice bath) can be measured by the 2nd standard
mercury thermometer. The standard device’s expanded uncertainty or tolerance
should be no more than one fifth of the instrument’s tolerance Δ, and enough
stability should be ensured for the standard device during calibration.
(2) Calibration Sequence: The sequence of “Ω→mV→INT” should be follow
during calibration, or carry on alone also. If Ω or mV calibration point is skipped
(Skip), then relevant Ω or mV calibration point will be invalid or skipped.
1) The sequence for Ω calibration points: 58Ω, 258Ω, It is the RTD four-wire
socket for input.
2) The sequence for mV calibration points: 0mV, 18mV, 58mV. It is the TC
socket for input.
(3) Calibration for Instrument Coefficients: Set CAL.Cod=808, and press “Key
4” for long to enter calibration. According to prompts, input each standard signal
value in a point-by-point way, in which, “xxxxr” indicates the input value of
xxxxΩ; and “xxxxm” indicates xxxxmV. The calibration operation diagram is as
follows.
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