4-12
Chapter 4. WIRING
Wiring with zener barriers
Take the following notes into account if connecting an RTD to the PV input of the
unit through a zener barrier.
• Be sure to adjust the zener barriers following the instructions in chapter 5. If the
unit is adjusted in combination with recommended zener barriers, the indication
accuracy of the PV input is up to ±0.5 %FS ±1 digit, depending upon the
instrumentation conditions.
• Set the unit's PV input range to a value other than Nos. 53−62, so that the
internal resistance of the zener barrier does not exceed the allowable resistance
for the range.
• Use zener barriers recommended by Azbil Corporation. With zener barriers that
do not meet the specifications below, accuracy may be dramatically degraded. If
unrecommended zener barriers are used, contact the azbil Group.
Internal resistance ≤ 85 Ω
(Note: Consider the wiring resistance as well as the internal resistance.)
Working voltage ≥ 1 V
Leakage current: ≤ 1 µA (at 1 V)
Recommended zener barriers (for RTD)
Product No. 8907/22-02/120 (Azbil Corporation)
Product No. NZB3-1R75 (Nakamura Electric Mfg. Co., Ltd.)
Take the following note into account if connecting an Thermocouple to the PV
input of the unit through a zener barrier.
• If the unit is adjusted in combination with recommended zener barriers, the
indication accuracy of PV input is up to ±0.5 % FS ±1 digit, depending on the
instrumentation conditions.
• Use zener barriers recommended by Azbil Corporation. With zener barriers that
do not meet the specifications below, accuracy may be dramatically degraded. If
unrecommended zener barriers are used, contact the azbil Group.
Working voltage ≥ 1 V
Leakage current: ≤ 1 µA (at 1 V)
Recommended zener barriers (for TC)
Product No. 8907/22-05/110 (Azbil Corporation)
Product No. NZB2-1R52 (Nakamura Electric Mfg. Co., Ltd.)
Noise preventive measures
The power is taken from the single-phase instrument power supply to consider
noise preventive measures.
If the noise from the power supply is large, an appropriate insulation transformer is
added to the power supply and an appropriate line filter must be used.
(Azbil Corporation's line filter model No.: 81442557-001)
If the noise has a fast rising edge, an appropriate CR filter must be used.
(Azbil Corporation's CR filter model No.: 81446365-001)
Handling Precautions
After the noise preventive measures have been taken, do not bundle the
primary and secondary sides of the insulation transformer together or lay/
route them in the same conduit or duct.
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