Altek Model 311A Universal RTD Calibrator Manual

							Universal RTD Calibrator
Model 311A
• Simulate RTDS into smart transmittersWorks with a wide variety of models including
Rosemount 3144 & Honeywell STT series
• Universal compatability with process
instruments
Operates with devices that use pulsed excitation
currents including PLCs, DCS and multi-channel
recorders
• Calibrate in °C & °F for your RTD typePlatinum 100Ω, copper 10Ωand 50Ω, nickel 110
and 120Ω
Simulate from 0.00 to 500.00 ohms
• Calibrate with laboratory accuracy±(0.01% of reading + 0.075 ohms)
Accurate to ±0.2 °C (0.4 °F*) for Pt 100 Ohm RTDs
• Resolution to 0.1 °C or °F & 0.01 ohm
• Digital accuracy with analog simplicity
Speed sensitive digital pot for fast output
adjustment
• Use settable “Quik-Chek©”Set any Span & Zero for instant recall
• Standard  “AA” alkaline batteries50 hours of constant operationCompatible with more instruments 
The Model 311A has been designed to calibrate every
type of RTD monitoring and measuring device. The
enhanced circuitry of the 311A makes it compatible
with a wider variety of instruments than other RTD
calibrators. 
Some newer process control equipment use a pulsed
excitation current to measure RTD sensors. This
includes some smart transmitters, multi-channel
recorders and inputs to programmable logic
controllers (PLCs), computers and digital control
systems.
The Model 311A is designed to work with these
devices and accepts intermittent current pulses as
short as 10 milliseconds. It calibrates devices with
excitation currents of as little as 0.090 mA and as high
as 10.20 mA
Simulate and read RTDs
Altek’s Model 311A RTD Calibrator lets you
SIMULATE and READ RTDs over the entire industrial
temperature range. Switch between four platinum 100
ranges and two ranges each for copper and nickel. 
Calibrate RTD instruments
Simulate RTD resistances into all types of measuring
instruments. The Altek Model 311A takes the place of
bulky, expensive decade boxes and temperature
tables. Output directly in °C, °F* or dial in the
resistance value in ohms.  
Quik-Chek outputs
Save time with every calibration by instantly recalling
three output settings for each RTD type with the
handy Quik-Chek switch. All output settings are
remembered, even with the power off.  
Read RTD sensors
The Model 311A display gives you fast, accurate
temperature measurement with 0.1° and 1° or
resistance measurement to 500.00 ohms with 0.01Ω
resolution. Two, three and four wire hookups assure
accuracy in long cable runs. Open RTDs and leads
are detected and indicated on the LCD display. Two
readings per second track fast moving temperatures. 
MAX and MIN memories are continuously updated
from turn-on or whenever the RESET button is
pressed. Model 311A gives you a handy tool to
monitor temperatures for drift or control deviation. Just
flip the Quik-Chek switch to display the minimum and
maximum temperature measured since reset.
General description 
						

							General instructions
Changing RTD typesEight RTD types or ohms may be selected to match
the sensors and instruments in your plant.
The symbol Alpha (α) is used to identify the
particular RTD curve. The value is derived by
dividing the resistance of the sensor at 100°C by the
resistance at 0°C (α= R100°C/R0°C). For Pt 100
DIN/IEC/JIS this is 138.50/100.00 = 1.3850. This
value is sometimes represented as 0.00385 or
simply as 385.
To change RTD types:
1) Turn the selector knob to the desired Metal (Pt,
Cu, Ni or to ohms. Note that for  the most
common RTD type, Pt 100ΩDIN/IEC/JIS a =
1.3850, there is a dedicated position on the
selector.
2) There are a choice of several a values for Pt, Ni
& Cu. Press the SETUP push-button to scroll
through the available a curves.
Changing batteriesLow battery is indicated by BAT on the LCD display.
Approximately 10 hours of operation remain before
the LCD goes blank and the Model 311A shuts itself
down. Turn the Model 311A off, loosen the screw on
the battery compartment and lift off the battery
compartment door. Replace the six “AA” batteries,
replace the door and tighten the screw.
ConnectionsThe Model 311A accurately simulates and reads 2,
3, or 4 wire RTDs. Press the 2, 3, 4 WIRE push-
button to match the instrument being calibrated. All
connecting wires must be the same length and of
the same material running along the same path to
insure maximum accuracy.
Two, three or four wireTwo wire RTD measurements are less accurate than
other RTD measurements because of the errors
introduced by the resistance of the lead wires. The
third wire in a three wire hookup provides the
instrumentation with a reference connection for the
lead wires. The measuring instrumentation uses this
reference to infer the actual resistance of the RTD
element without the leads. Four wire RTD
measurements take into account all wires other than
the RTD sensing element. This makes four wire
RTDs best suited for precision measurements.
Compatibility with excitation
currents
RTD measuring instruments use different levels of
excitation current to read RTDs. The 311A operates
with excitation currents from 0.090 to 10.20 mA. As
the excitation current increases the highest
resistance that can be simulated decreases. With
currents from 0.090 to 5.0 mA the 311A can simulate
up to 500.00Ω. At 10.20 mA the highest simulated
resistance is 250Ω.
Some transmitters, recorders and other RTD input 
devices use intermittent, or pulsed, excitation
currents to measure the resistance of the RTD. The
Model 311A operates with both steady excitation
currents and with intermittent currents as fast as 10
milliseconds.
User options
Auto-offThe 311A can be set up to turn itself off after 30 minutes of
inactivity. The internal timer is reset to 30 minutes each time the
digital pot is turned or a push-button is pressed. This configuration
is part of the User options.
Configuring temperature scales*The 311A may be configured for full time use of °C, full time use of
°F or selectable °C and °F operation. This configuration is part of
the User Options.
Selecting autoranging or 1° resolutionThe Model 311A may be configured to autorange or to constantly
display with fixed resolution. When autoranging is selected, the
Model 311A will display temperatures with 0.1° or 1° resolution.
When fixed range is selected, the Model 311A will display
temperatures with 1° resolution.This configuration is part of the
User options.
Note: Some ranges are always displayed with 1° resolution.
Operation with noisy excitation currentsThe Model 311A automatically adapts itself to work with steady and
pulsed excitation currents. Sometimes, the 311A may not properly
detect the excitation current, especially when the excitation current
is disturbed by electrical noise generated by the device being
calibrated. When noisy current mode is on the 311A will operate as
if all excitation currents are pulsed at less than 56 milliseconds.   
User optionsThe 311A may be restored to the factory settings. This will reset the
HI, SET and LO “QUIK-CHEK” memories for all RTD types to 0 °C
(32 °F) and the Ωrange to 100Ω. Prompts also guide you for
selection of Auto-Off, temperature scale(s) and resolution.
1) Press and hold the STORE/RESET push-button while turning
the 311A on.
2) Keep holding the STORE/RESET push-button until the display
flashes (about three seconds) then release.The revision number
of the firmware will be displayed for a few seconds.
3) After three seconds the words SETUP, BAT and on will appear
on the display indicating that AUTO-OFF is selected.
4) To toggle the AUTO-OFF function on and off press the SETUP
push-button and the words on and OFF will display.
5) After three seconds the 311A will automatically store your choice
and the  word SETUP, and the symbols °C & °F will display*.
6) Press the SETUP push-button to make your selection. With °C
flashing the unit will only display in °C, With °F flashing the unit
will only display in °F and with both flashing you can select °C
and °F for each T/C & RTD type. °C/°F is selected if no push-
buttons are pressed.
7) After three seconds the 311A will automatically store your choice
and the word SETUP and 0.1° will appear on the display.
8) To toggle the resolution press the SETUP push-button to switch
between 0.1° and 1°.
9) After three seconds the 311 will automatically store your choice
and the words SETUP, OFF and a symbol for pulsed current (a
waveform) will display indicating that noisy current compatibility
is off.
10) To toggle noisy current compatibility on and off press the
SETUP push-button and the words on and OFF will display.
11)After three seconds the 311A will automatically store your choice
and the 311A will begin normal operation.
Pt
Cu
Ni
Ω
SETUP
WIRE 2, 3, 4
Pulsed Current
Steady Current 
						

							Simulate an RTD
Source1) Set up the Model 311A for the correct RTD 
type (and temperature scale*). 
2) Disconnect the input wires from the device 
to be calibrated or checked.
3) Connect the Model 311A to the device to be 
calibrated, being careful to observe proper 
connections for 2, 3 or 4-wire hookups.
4) Turn the digital pot to the desired output value. 
OutputWhenever source is selected the word SOURCE will
appear on the LCD. SOURCE will flash when the
Model 311A is measuring the external excitation
current and will be steady when accurately
simulating a resistance. To change the output value,
turn the speed sensitive digital pot. Turning the pot
slowly will cause a gradual change in the output. A
faster change will occur when the pot is turned
faster. This function operates in all three output
positions (HI, SET & LO). 
Note: Flashing digits on the display indicates that
the excitation current produced by the device being
calibratred is below 0.09 mA or that no excitaion
current is present. Excitaion currents over 10.2 mA
are indicated by – – – – – on the display. Check to
see that the device being calibrated has operating
power and that the 311A is properly connected. Also
check the manual for the device to make sure that
the excitation current is in the range of 0.090 to
10.20 milliamps.
Store1) Switch to HI (or LO).
2) Turn the digital pot to desired value.
3) Press STORE push button.
If a value is in the SET position and you want
that value in HI or LO, press and hold the
STORE button while moving the switch to HI or
LO. Then release the STORE button. When
there is no excitation current or the current is
less than 0.09 mA, the digits will flash on the
LCD. “Quik-Chek” values may still be stored with
the digits flashing.
Quik-ChekAny time you need a stored value just throw the
Quik-Chek switch. Any value in the RTD range may
be stored in HI & LO. The Model 311A remembers
the HI, LO and SET values for you with the power
on or off. When a new RTD type is selected, 0°C is
stored in all Quik-Chek positions. When the ohms
range is selected, 100.00Ωwill be the initial setting
for all Quik-Chek positions.
A symbol indicates that intermittent currents
faster than 56 milliseconds have been detected.
With these fast excitation cureent pulses the 311A
assumes that the exciation current is between 0.09
and 10.2 mA.
Read an RTD sensor
Read1) Set up the Model 311A for the correct RTD type
(and temperature scale*).
2) Disconnect the wires from the resistance sensor
to be read or checked.
3) Connect the Model 311A to the sensor to be
measured, being careful to observe proper
connections for 2, 3 or 4-wire hookups.
4) Display present reading, Maximum or Minimum
temperature.
InputWhenever READ mode is selected the word READ
will appear on the LCD. The Model 311A can
measure temperatures with resolution of 0.1° and 1°
and resistance to 500.00Ωwith resolution of 0.01Ω.
The display is updated twice per second to
continuously track fast moving temperatures. Using
three or 4-wire hookups provides accurate readings
in long cable runs.
Open RTDsThe Model 311A checks for open or high resistance
connections. Open or burned out RTDS are
indicated by - - - - - on the display.
If the temperature is out of range the symbols or
and ur will appear on the display.
MIN/MAXTo read the Maximum or Minimum temperature
since READ mode was entered, simply switch to
MAX or MIN. The value will appear on the LCD
along with the word MAX or MIN. The MAX/MIN
values are automatically updated and may be
viewed at any time without disturbing the other
values. Pressing RESET will transfer the present
temperature into both MAX and MIN and will update 
them as the measured temperature changes.
The Model 311A can be hooked up to instruments or sensors with
two, three or four wire connections. Use the diagram on the
connection panel (shown on the right) and match the resistor
symbol to the diagram on the instrument, sensor or the manual for
the instrument. For two wire connections, place a red lead in socket
1 and a black lead in socket 2. For three wire connections place a
red lead in socket 1, and black leads in sockets 2 and 3. For four
wire connections place red leads in sockets 1 and 4 and black
leads in sockets 2 and 3.
Connections
SOURCEHI
SET
LO
RESET STORE
SOURCEHI
SET
LO
READ SOURCE
°C / °F
WIRE 2, 3, 4
READMIN READMAX
READ SOURCE
°C / °F
WIRE 2, 3, 4
14
2
3 
						

							PN 1887711 Rev A April 2002
©2002 Altek Industries, Inc. Specifications subject to change without notice. 
All rights reserved. Printed in U.S.A.  
Altek products are warranted to be free from defects
in material and workmanship (excluding fuses,
batteries and leads) for a period of three years from
the date of shipment. Warranty repairs can be
obtained by returning the equipment prepaid to our
factory. Products will be replaced, repaired, or
adjusted at our option. Altek gives no other
warranties, including any implied warranty of fitness
for a particular purpose.Also, Altek shall not be liable
for any special, indirect, incidental or consequential
damages or losses arising from the sale or use of its
products.
Warranty
(Unless otherwise Indicated, specifications are in % Span in ohms
with 1 mA fixed excitation current @ 23° C)
GeneralGeneral accuracy: ±(0.01% of reading + 0.075 ohms)
Temperature drift: ± 0.01% / °C
Operating temperature range: -5 to 140 °F (-20  to 60 °C)
Storage temperature range: -22 to 170 °F (-30 to 80 °C)
Relative humidity: 10 to 90%, non-condensing
Warm-up time: 30 seconds to maximum accuracy
Battery life:  6  “AA” Alkaline Batteries:  Nominal 50 hours
Low battery: “BAT” indication on LCD at 7 volts nominal,
approximately 10 hours left.  Batteries should be removed when
storing the unit for longer than three months.
Overall size:  6.23 x 3.27 x 1.94 inches (158.1 x 83.1x 49.3 mm)
Weight: 1lb, 2oz (0.5 kg)
Specifications
Source (Simulation of RTD or resistance)Output resistance range: 0.00 to 500.00 ohms
Accuracy from 1 to 10.2 mA of external excitation current:
±(0.01% of reading + 0.075 ohms)
Accuracy below 1 mA of external excitation current:
±(0.01% of reading +                                  + 0.05 ohms)
Allowable external excitation current: 0.09 to 10.20 mA
Intermittent excitation currents: Accepts intermittent excitation
currents with minimum of 10 milliseconds fixed current at minimum
repetition rate of 1 every five seconds from 0.09 to 10.20 mA.
Read (Measure an RTD or resistance)Input resistance range: 0.00 to 500.00 ohms
Accuracy: ±(0.01% of reading + 0.075 ohms)
Excitation current supplied: 1 mA, nominal
Normal mode rejection:  50/60 Hz, 50 db
Common mode rejection:  50/60 Hz, 100 db
Ranges and accuracy
0.025 mV
mA Excitation Current
(Temperature Accuracies Converted From Resistance  – Based On Ohms Accuracy of ±(0.01% of Reading + 0.075Ω)
RTD TYPE ALPHA RANGE ACCURACY RANGE               ACCURACY
Pt 100Ω(DIN/IEC/JIS 1989)     1.3850 -200.0 to 200.0°C ±0.2°C -328.0 to 392.0°F ±0.4°F
Based on ITS-90 200.0 to 600.0°C ±0.3°C 392.0 to 1112.0°F ±0.6°F
600.0 to 850.0°C ±0.4°C 1112.0 to 1562.0°F ±0.7°F
Pt 100 (Burns) 1.3902 -195.6 to 200.0°C ±0.2°C -320.0 to 392.0°F ± 0.4°F
200.0 to 648.9°C ±0.3°C 392.0 to 1200.0°F ±0.6°F
Pt 100 (Old JIS 1981) 1.3916 -200.0 to 200.0°C ±0.2°C -328.0 to 392.0°F ±0.4°F
200.0 to 648.9°C ±0.3°C 392.0 to 1200.0°F ±0.6°F
Pt 100 (US Lab)                      1.3926 -200.0 to 100.0°C ±0.2°C -328.0 to 212.0°F ±0.4°F
100.0 to 700.0°C ±0.3°C 212.0 to 1292.0°F ±0.6°F
700.0 to 862.2°C ±0.4°C 1262.0 to 1584.0°F ±0.7°F
Cu 10 (Minco)                         1.4274 -200 to 260°C ±2°C -328 to 500°F ±4°F
Cu 50 1.4280 -50 to 150°C ±1°C -58 to 302°F ±1°F
Ni 120 (Pure) 1.6720 -80.0 to 315.6°C ±0.1°C -112.0 to 600.0°F ±0.2°F
Ni 110 (Bristol 7 NA) 1.5801 -106.7 to 315.6°C ±0.2°C -160.0 to 600.0°F ±0.3°F
Ohms 0.00 to 500.00 Ω±(0.01% of Reading + 0.075Ω)
* SI
On SI labeled instruments, all non-SI engineering units have been
disabled.