Pyromation 401 User Manual

INSTALLATION AND OPERATING INSTRUCTIONS
SERIES 401 RTD TEMPERATURE TRANSMITTER

General Information

The Pyromation Series 401 RTD temperature transmitter is a “two wire” loop powered resistance to current
transducer. This transmitter will produce a linearized (4 to 20) mA dc output current proportional to the
temperature of the RTD temperature sensor.

The transmitter’s small size allows universal mounting
inside Series 300, 400, and 900 screw cover heads,
Series 800 explosion-proof, therm ostat housings, and
panel surface mounting us ing two 6-32 screws

1

. The
transmitter is designed for an operating ambient
temperature of (-30 to 65)

°C [(-22 to 149) °F].

Power Supply
The transmitter is designed f or a nom inal 24 V dc power supply. The trans m itter will operate over a range of (9 to

36) V dc depending on the resistive load. Use the following for mulas to deter mine the m axim um r esistive loading
(RL) allowed for the power us ed, or to determine minimum supply voltage (V) required for fixed resistive loads.
The formulas assume a maximum current of 20 mA.

VMIN = 20 mA × RLOAD + 9 V dc RMAXLOAD = (VSUPPLY – 9 V dc ) / 20 mA

One power supply can be used for several transmitter loops. Each loop must have only one transmitter in it and all
loops must be wired in parallel. Do not forget to observe the maximum current rating for your power supply.

Note: If used in a manner not specified by the manufacture, the protection provided by the equipment may be impaired.

Wiring
The terminal block on the trans mitter c an accept wire from 14 to 24 gauge. Shielded or c onduit encased (twisted
pair) cable is required from the transmitter to the controller, including the sensing element and lead wire. Note that
low voltage lines should be run in separate conduit isolated from high voltage or high current carrying lines.

Note 1

RTD ELEMENT

COPPER LEADS

Open Sensor Indication

When an RTD has failed due to an open sensor, the transmitter will
indicate an error. The way the error is produced is by either driving the
current low, under 4 m A (downscale burnout) or by driving the current
high, above 20 mA (upscale burnout). Upscale burnout is standard for
all Pyromation transmitters.

However, the burnout indication does not apply to a break in the lead
compensation loop. In this case, the burnout signal will drive the
transmitter either high or low depending upon which lead has broken.

CONTROLLER

POWER
SUPPLY

5211 Industrial Road • Fort Wayne, IN 46825 USA • [phone] FAX: [phone] • http://www.pyromation.com 3/02

 Copyright 2002 Pyromation, Inc. All rights reserved. Form 401f

INSTALLATION AND OPERATING INSTRUCTIONS
SERIES 401 RTD TEMPERATURE TRANSMITTER

Troubleshooting

Problem Possible Causes

No Current Flow in Signal Loop

Current Over 20 mA

Erratic Readings

Destructive Errors

Non-Destructive Errors

Calibration

Pyromation RTD transmitters are factory calibrated. If recalibration is necessary, a zero and span adjustment can
be made from the top of the unit.

Note: adjustment to calibration will void warranty

1. Remove the RTD sensor wires and attach a RTD simulator.

2. Apply a simulated ‘zero’ resistance input and adjust the zero potentiometer for 4.00 mA output.

3. Apply a simulated ‘span’ resistance input and adjust the span potentiometer for 20.00 mA output.

4. The zero and span adjustments are interactive. Repeat steps 2 and 3 as necessary.

Application Hints
The calibrated output of the Pyromation transm itter is (4 to 20) mA. However, the lower and upper limits of output
current are approximately (2.2 and 30) mA respectively. This means that for a system using a 250 ohm resistor
( 1 to 5) V, the maximum voltage could be as high as 7.5 volts ( 30 mA x 250

Some computer bas ed systems will not tolerate input voltages greater than approximately 5.5 volts. Instead of
selecting a different scaling resister (167
with the scaling resist or will c lam p the voltage ac ross the sc aling resis tor to 5.1 V while still allowing the calibrated
range to remain (1 to 5) V.

Limited Warranty

THE SERIES 401 RTD TEMPERATURE TRANSMITTER SOLD BY OR PURCHASED FROM PYROMATION, INC. OR FROM AN AUTHORIZED
PYROMATION, INC. DISTRIBUTOR, OR AGENT IS SUBJECT TO THE FOLLOWING LIMITED WARRANTY.

This product is warranted to be free from functional defects in materials and workmanship at the time the product leaves the Pyromation, Inc. factory, and to conform at that same time to the
specifications set forth in the relevant Pyromation, Inc. installation, wiring, operati on manual for this product for a period of one year after shipment from the Pyromation, Inc. factory.

Pyromation’s exclusive and sole obligati on, and Buyer’s exclusive and sole remedy under the above Limited Warranty is limited to either repair or replacement of such product, at
Pyromation’s option, free of charge to Buyer. Pyromation shall have no obligation to repair or repl ace unless the claimed defect in material or workmanship is reported in writing to
Pyromation at 5211 Industrial Road, Fort Wayne, Indiana 46825 within ten (10) days after delivery to the Buyer from Pyromation or an authorized Pyromation distributor, representative or
reseller. If so requested by Pyromation, the product shall be returned to a designated facility during normal business hours, transportation prepaid.

Any action for breach of this warranty or other action arising out of this contract must be commenced within one year after delivery.
Pyromation shall not be liable for any warranty, express or implied, other than the warranty stated above, and in the event of a breach of the above stated warranty, Pyromation shall not be

liable for any incidental, consequential , special, or other damages, costs, or expenses other than repair or replacement as described above. Pyromation excludes any and all warranties of
merchantability or fitness for a particular purpose. The above stated warranty extends only to the original Buyer from Pyromation, Inc. or from an authorized Pyromation distributor or agent,
and may not be transferred or assigned.

• Current loop may be open at some point

• No Voltage out at power supply

• Reverse polarity on loop connection

• RTD is open

• Current loop connections shorted

• Loose connection in RTD or signal loop

• Damaged RTD

• AC noise on loop connections

• Exceeds loop resistance RL

• Do not connect power to the RTD input; this could destroy the unit

• Do not connect power to the RTD sensor

• Do not use AC line power

• Reverse polarity on loop connection

• Do not connect multiple transmitter in series

Ω ) in the case of an open RTD.

Ω for example gives 5 V for an open RTD), a 5.1 V zener diode in parallel

5211 Industrial Road • Fort Wayne, IN 46825 USA • [phone] FAX: [phone] • http://www.pyromation.com 3/02

 Copyright 2002 Pyromation, Inc. All rights reserved. Form 401f