Micromod MOD: MODCELL Multiloop Processor 2002N Model C and Associated Hardware User Manual

Page 34

MODCELL Multiloop Processor

ELECTRICAL CONNECTIONS

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Any connection made to provide a noise ground should be kept as short as possible
using the largest practical wire gauge. This is necessary to keep the inductance of
the connection as low as possible. Bear in mind that noise spikes have very short rise
times and that any inductance will appear as a high impedance.

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For best noise reduction performance the microprocessor-based device's ground
terminal should be connected to a nearby grounded large metal structure, using the
shortest length wire possible. If a three-wire cordset is used to power the
microprocessor-based device through a receptacle, the ground wire is generally too
long and too noisy to be a good ground.

3.5

PROCESS INPUT SIGNAL CONNECTIONS

This section describes the process input connections for the following input module types:

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2013A Thermocouple Input Module with upscale burnout detection (Section 3.5.1)

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2004A Solid-State Relay Input Module (Section 3.5.2)

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2006A Nonisolated Digital Input Module (Section 3.5.3)

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2002A Current Input Module (Section 3.5.4)

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2012A Current Input Module with Two-Wire Transmitter (Section 3.5.4)

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2001A Voltage Input Module (Section 3.5.5)

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2009A RTD Input Module (Section 3.5.6)

3.5.1 Thermocouple and Cold Junction Compensation Input

Make thermocouple connections as shown in Figure 3-3. At least one cold junction
compensation input is recommended for each controller to sense the temperature at the
terminal block. Use a 2009AZ102*0A 2-wire RTD Input Module with RTD sensor as
described in Section 3.5.6 for cold junction compensation. Thermocouple input
specifications are:

THERMOCOUPLE INPUT (with upscale burnout detection)

Types: B,E,J,K,N,R,S,T
Range: ±100 mV DC (See Table 3-1 for temperature range limits )
Low limit: - 110 mV
Upper limit: + 110 mV
Input Resistance: 10 Megohms
Noise filter: 3 db at 3 Hz
Resolution: 16 bits
Sensitivity: 4 uV
Accuracy (calibrated): ±0.1% of span
Isolation : 250 Vrms
Max Survivable Input: ±300 VDC or 250 VAC (Differential)
Common mode rejection: 100 db at 60 Hz typical
Normal mode rejection: 40 db at 60 Hz typical