Input Specifications; Sensor Input Configuration - Lakeshore 325 User Manual

Model 325 Specifications
Input Specifications
Sensor
Temperature
Coefficient
Diode negative
negative
PTC RTD positive
positive
NTC RTD negative
Thermocouple positive
positive
11 Control stability of the electronics only, in an ideal thermal system
12 Current source error has negligible effect on measurement accuracy
13 Diode input excitation current can be set to 1 mA – refer to the Model 325 user manual for details
Thermometry
Number of inputs 2
Input configuration Each input is factory configured for either diode/RTD
or thermocouple
Isolation Sensor inputs optically isolated from other circuits
but not each other
A/D resolution 24-bit
Input accuracy Sensor dependent – refer to Input Specifications table
Measurement resolution Sensor dependent – refer to Input Specifications table
Maximum update rate 10 rdg/s on each input (except 5 rdg/s on input A when
configured as thermocouple)
User curves Room for 15 200-point CalCurves™ or user curves
SoftCal™ Improves accuracy of DT-470 diode to ±0.25 K
from 30 K to 375 K; improves accuracy of platinum RTDs to
±0.25 K from 70 K to 325 K; stored as user curves
Filter Averages 2 to 64 input readings
Sensor Input Configuration
Diode/RTD
Measurement type 4-lead differential
Excitation Constant current with
current reversal for RTDs
Supported sensors Diodes: Silicon, GaAlAs
RTDs: 100 Ω Platinum,
1000 Ω Platinum, Germanium,
Carbon-Glass, Cernox™,
and Rox™
Standard curves DT-470, DT-500D, DT-670,
PT-100, PT-1000,
RX-102A, RX-202A
Input connector 6-pin DIN
6
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Input Excitation
Range Current
0 V to 2.5 V 10 µA ±0.05%
12, 13
0 V to 7.5 V 10 µA ±0.05%
12, 13
0 Ω to 500 Ω 1 mA
14
0 Ω to 5000 Ω
1 mA
14
0 Ω to 7500 Ω
10 µA ±0.05%
14
±25 mV NA
±50 mV NA
Thermocouple
2-lead, room temperature
compensated
NA
Most thermocouple types
Type E, Type K, Type T,
AuFe 0.07% vs. Cr,
AuFe 0.03% vs. Cr
Ceramic isothermal block
Display Measurement
Resolution Resolution
100 µV 10 µV
100 µV 20 µV
10 mΩ 2 mΩ
100 mΩ 20 mΩ
100 mΩ 40 mΩ
1 µV 0.4 µV
1 µV 0.4 µV
14 Current source error is removed during calibration
Accuracy specification does not include errors from
15
room temperature compensation
Control
Control loops 2
Control type Closed loop digital PID with manual heater output or open loop
Tuning Autotune (one loop at a time), PID, PID zones
Control stability Sensor dependent – see Input Specification table
PID control settings
Proportional (gain) 0 to 1000 with 0.1 setting resolution
Integral (reset) 1 to 1000 (1000/s) with 0.1 setting resolution
Derivative (rate) 1 to 200% with 1% resolution
Manual output 0 to 100% with 0.01% setting resolution
Zone control 10 temperature zones with P , I, D, manual heater out,
and heater range
Setpoint ramping 0.1 K/min to 100 K/min
Safety limits Curve temperature, power up heater off, short circuit protection
Electronic Electronic
Accuracy Control
Stability
±80 µV ±0.005% of rdg ±20 µV
±80 µV ±0.01% of rdg ±40 µV
±0.004 Ω ±0.01% of rdg ±4 mΩ
±0.04 Ω ±0.02% of rdg
±40 mΩ
±0.1 Ω ±0.04% of rdg
±80 mΩ
±1 µV ±0.05% of rdg ±0.8 µV
15
±1 µV ±0.05% of rdg ±0.8 µV
15
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