Eaton ELCM Series, Руководство по эксплуатации

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3. AIAO Units
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3.1.4 ELC-PT04ANNN
3.1.4.1 The Basic Concepts of Platinum Temperature Sensors (PT100)
Platinum temperature sensor is highly accurate and stable and the quality of linearity between
-200°C and 600°C is fairy good. Generally speaking, the temperature coefficient of PT100
temperature sensors is significant at low temperatures -200°C ~ -100°C, and the quality of
linearity is good at middle temperature 100°C ~ 300°C. The temperature coefficient becomes
small for higher temperatures, i.e. 300°C ~ 500°C. The resistance of PT100 is 100 Ω when the
temperature is 0°C, which is the standard for a metallic temperature sensor.
The rated current for temperature sensore should be less than 2mA. The self-heating of 1mW for
a PT100 will cause a temperature variation of 0.02°C ~ 0.75°C. Therefore, reducing the current
of a PT100 can also reduce the temperature variation. However, if the current is too small, the
PT100 signal can be affected by electrical noise. For this reason, it is recommended to confine
the current to the range 0.5mA and 2mA.
3.1.4.2 Introduction
The ELC-PT04ANNN allows the connection of four platinum temperature sensors (PT100
3-WIRE 100 Ω 3850 PPM/
°
C(DIN 43760 JIS C1604-1989)). The ELC Platinum Thermocouple
module converts the sensor inputs into a 14 bit digital value, which may then be read into the
ladder program by using TO and FROM instructions. There are 49 Controlled Registers (CR) in
this module (each register is 16 bits). The ELC controller program can read/write the CR data of
the Platinum Temperature Sensor Module, ELC-PT04ANNN using the FROM / TO instructions.
3.1.4.3 Specification
„
Functional Specifications
Temperature
measurement module
Celsius (°C) Fahrenheit (°F)
Power supply voltage 24V DC (20.4V DC ~ 28.8V DC) (-15% ~ +20%)
Analog input channel 4 channels/module
Applicable sensors type 3-WIRE PT100 Ω 3850 PPM/°C (DIN 43760 JIS C1604-1989)
Current excitation 1mA
Temperature input range -200 ~ 600 -328 ~ 1,112
Range of digital
conversion
K-2,000 ~ K6,000 K-3,280 ~ K11,120
Resolution 14 bits (0.1°C) 14 bits (0.1°F)
Overall accuracy
±0.5% when in full scale (25°C, 77°F)
±1% when in full scale within the range of 0 ~ 55°C, 32 ~ 131°F
Response time 200ms × the number of channels
Isolation
Isolation between digital area and analog area. No isolation among
channels.
Digital data format 13 significant bits out of 16 bits are available; in 2’s complement.