Practical Instrument Electronics
Example 1:
4-20 Milliamp/Voltage
Loop Calibrator
with Loop Diagnostic
TECH NOTE 1
Do you think your loop is calibrated correctly?
Think again!
UNDETECTED LONG STANDING FIELD CALIBRATION ERROR
20mA - i Leakage
FIELD
TRANSMITTER
Actual Field Transmitter
Current 19.976 mA!
1 Meg W
Remote leakage resistance
from fault and/or corroded
connections.
Undetected Calibration
i
ERROR!
Leakage
20mA
+24V
20.000 mA
CALIBRATED
DCS INPUT
Model 532
Example 2:
Solution:
Using the Model 532
in power measure mode,
using loop diagnostic.
UNDETECTED CALIBRATION ERROR USING OTHER CALIBRATORS
20mA - i Leakage
FIELD
TRANSMITTER
Actual Field Transmitter
Current 19.976 mA!
1 Meg W
Remote leakage resistance
from fault and/or corroded
connections.
i
Leakage
20mA
Undetected Calibration
ERROR!
CALIBRATION ERROR DETECTED USING THE MODEL 532
20mA - i Leakage
FIELD
TRANSMITTER
Actual Field Transmitter
Current 19.976 mA!
1 Meg W
Remote leakage resistance
from fault and/or corroded
connections.
i
Leakage
20mA
DC mA DC V DC W
20.00 24.0
POWER MEASURE DIAG
leakage =
AC V = 00.0
00.02mA
01200
841 Holt Road #1 Webster, NY 14580
Practical Instrument Electronics, Inc.
i Leakage Error of 0.02 mA Detected!
DETECTED!
Calibration Error
Tel: 585-872-9350 Fax: 585-872-2638
Copyright 2003. All rights reserved.
Patent Pending
sales@piecal.com http://www.piecal.com
Tech Note 1
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