4200 Series Transmitters
Instruction Manual
Form 5596
November 2006
17
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A Type 4212 or 4222 position switch (without
the transmitter) obtains stem position from the input
potentiometer and provides position switch outputs
from relays K1 and K2 (figures 4 and 9). The high
position switch circuit output controls relay K1
mounted on the field circuit printed wiring board and,
the relay contacts connect to TB1. The low position
switch circuit output controls relay K2 and, the relay
contacts connect to TB2. Deadband is the difference
between trip and reset points of a relay.
D
A Type 4215 transmitter obtains position
information from a dual potentiometer on the same
shaft, which allows for individual potentiometers for
the transmitter circuit and the position switch circuits.
The transmitter input is from one of the
potentiometers and its output connects to TB3
(figure 6) mounted on the field circuit printed wiring
board. The position switch input is obtained from the
other potentiometer.
The high position switch circuit output controls relay
K1 mounted on the field circuit printed wiring board
and the relay contacts connect to TB1. The low
position switch circuit output controls relay K2 and
the relay contacts connect to TB2. The relationship
between the transmitter output, relay position switch
outputs, and deadband is shown in figure 7.
Deadband is the difference between the trip and
reset points of a relay.
Normal Operation
WARNING
On an explosion-proof instrument,
remove electrical power before
removing the instrument covers in a
hazardous area. Personal injury or
property damage may result from fire
or explosion if power is applied to the
instrument with the covers removed, in
a hazardous area.
Once the instrument has been calibrated and placed
in operation, further adjustments should not be
necessary. The 4 to 20 milliampere output can be
monitored during operation (in a non-hazardous
environment) by removing the cover and connecting
a milliammeter between TP1 (+) and TP2 (
−
) on the
printed wiring board (figure 5) on Type 4210, 4211,
4215, 4220, or 4221 transmitter. On Type 4212 or
4222 connect a voltmeter between TP5 (+) and TP6
(
−
) to measure potentiometer position.
For position switch circuits, the switching condition
can be monitored by observing the indicating device
or using an ohmmeter connected to the terminal
blocks (TB1 and TB2) in the field wiring
compartment. Refer to the Calibration section for the
test setup.
Calibration
Note
The potentiometer alignment
procedures, in the Installation section,
must be completed before performing
instrument calibration. Also, be sure
the direct or reverse action is correct
for the application.
Calibration of the instrument consists of adjusting
the zero and span of the transmitter and/or adjusting
the high and low position switches for a specific
travel. The high and low position switches also have
deadband adjustments that are made during the
calibration procedures. Refer to figure 7 for
transmitter and position switch conditions.
For a Type 4212 or 4222 instrument with position
switch circuits only, refer to the high and low position
switch adjustment procedures in this section. For a
transmitter with or without position switch circuits,
refer to the transmitter circuit zero and span
adjustment procedures in this section.
If satisfactory results cannot be obtained during
calibration, refer to the appropriate procedures in the
Maintenance section.
Test Equipment Required
The following test equipment is used in the
calibration and maintenance of the instrument:
D
Digital voltmeter (DVM) that measures voltages
in the range of 0 to 30 volts dc with an accuracy of
±
0.25 percent.
D
Power supply capable of supplying 20 to 30 volts
dc at 100 milliamperes.
D
Resistor, 250 ohms, 0.1%, 0.5 watt or greater.
