Dwyer MS User Manual

Series MS Magnesense®Differential Pressure Transmitter

Specifications - Installation and Operating Instructions

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The Series MS Magnesense®Differential Pressure Transmitter is an
extremely versatile transmitter for monitoring pressure and air velocity.
This compact package is loaded with features such as: field selectable
English or metric ranges, field upgradeable LCD display and the ability
to select a square root output for use with pitot tubes and other similar
flow sensors. Also, a single digital push button simultaneously calibrates
both zero and span reducing installation and setup time. These features
along with exceptional long term performance enables the Magnesense
to be the solution for a myriad of pressure and air flow applications.

INSTALLATION
Mounting:

The transmitter should be mounted on a vertical surface with the
connections directed down to prevent moisture from entering either the
pressure ports or the electrical cable entry.
Mount the transmitter using #8 x 1/2˝ pan head sheet metal screws in the
mounting flanges. Do not over tighten.

Electrical Connection:
2-Wire Operation:

CAUTION

WARRANTY WILL RESULT. 2-WIRE UNITS ARE NOT DESIGNED FOR AC
VOLTAGE OPERATION.

DO NOT EXCEED SPECIFIED SUPPLY VOLTAGE
RATINGS. PERMANENT DAMAGE NOT COVERED BY

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Bulletin A-26P

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Wall Mount Bracket

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DIN Mount Bracket

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SPECIFICATIONS
Service: Air and non-combustible, compatible gases.
Wetted Materials: Consult factory.
Accuracy: ±1% @ standard conditions.
Stability: ±1% F.S./ year.
Temperature Limits: 0 to 150°F (-18 to 66°C).
Pressure Limits:

1 psi (6.89 kPa) maximum, operation;
10 psi (68.9 kPa), burst.

Power Requirements:

2-wire, 10 to 35 VDC;
3-wire, 17 to 36 VDC or isolated 21.6 to 33 VAC.

Output Signals:

2-wire, 4 to 20 mA;
3-wire, 0 to 10 V or 0 to 5 V.

Response Time: 300 msec.
Pressure Calibration: One digital push button set both zero & span

simultaneously.

Loop Resistance:

Current output: 0 to 1250 ohm max.;
Voltage output: min. load resistance 1 k ohmΩ.

Current Consumption: 40 mA max.
Display (optional): 4 digit LCD.
Electrical Connections:

4 to 20 mA units: 2-wire: European style terminal block for
16 to 26 AWG;
0 to 10 V units: 3-wire: European style terminal block 16 to 22 AWG.

Electrical Entry: 1/2˝ NPS thread.

Accessory: A-151 cable gland for 5 to 10 mm diameter cable.

Process Connections: 3/16˝ (5 mm) ID tubing. Maximum OD 9 mm.
Enclosure Rating: NEMA 4X (IP65).
Mounting Orientation: Insensitive to mounting orientation.
Weight: 8.0 oz (230 g).
Agency Approval: CE.

The following standards were used for CE approval:

CENELEC EN 61000-4-2: 2001
CENELEC EN 61000-4-3: 2002
CENELEC EN 61000-4-4: 1995
CENELEC EN 61000-4-5: 2001
CENELEC EN 61000-4-6: 2003
CENELEC EN 61000-4-8: 2001
CENELEC EN 55011: 2003
CENELEC EN 61326: 2002
89/336/EED EMC Directive

DWYER INSTRUMENTS, INC.

Phone: [phone] www.dwyer-inst.com

P.O. Box 373 • Michigan City, IN 46361-0373, U.S.A. Fax: [phone] e-mail: [e-mail]

Electrical Connection:

V

–

+

+
–

RL

P.S.

POWER SUPPLY

17 TO 36 VDC

OR

21.6 TO 33 VAC

RECEIVER

CONN6

+
V
Ø

R

L

2-Wire Operation, continued:

The connections to the transmitter are made through a two circuit
European style terminal block CONN6 located at the bottom of the main
PCB board. Polarity is indicated by + and – signs on the PCB board. Do
not connect to the (V) terminal.

Figure 1

An external power supply delivering 10 to 35 VDC with a minimum
current capability of 40 milliamps must be used to power the control loop
in which the Magnesense®transmitter is connected. Refer to Fig. 1 for
connection of the power supply, transmitter and receiver. The range of
appropriate receiver load resistances (RL) for the power supply voltage
available is given by the formula and graph in Fig. 2. Shielded two wire
cable is recommended for control loop wiring and the negative side of the
loop may be grounded if desired. Note also that the receiver may be
connected in either the negative or positive side of the loop, whichever is
most convenient. Should polarity of the transmitter or receiver be
inadvertently reversed, the loop will not function properly but no damage
will be done to the transmitter.

1500
1400
1300
1200
1100
1000

900
800
700
600
500
400

TOTAL RECEIVER RESISTANCE (Ω)

300
200
100

50

0

RL MAX =

5101315

MAXIMUM VALUE (1250 Ω )

V

ps - 10.0

20mA DC

OPERATING

REGION

20 25 30 35 40

The connections to the transmitter are made through a three circuit
European style terminal block. Connect the power and signal leads to the
corresponding terminals as shown in Fig. 3. When using a DC supply,
the positive of the supply should be connected to (+) and the negative
connected to (-). Connecting the leads in reverse will not damage the
device but it will not operate. The DC supply should be capable of
providing 20 mA or more of current per Magnesense®transmitter.

When using an isolated AC supply, either leads of the supply may be
connected to (-) and (+). The input diode of the device half wave rectifies
and filters the applied AC voltage. A small DC current of less than 20 mA
is thus drawn through the transformer. The transformer used for the AC
supply must be capable of handling this small DC current. Use a UL 1584
Class 2 rated transformer rated between 24 V and 30 VAC, 40 VA or
larger, 50/60 Hz. UL 1584 Class 2 rated transformers are limited to 30
VAC maximum under any conditions at nominal line. The AC input
voltage to the device is thus limited to a minimum of 21.6 at low line (24
V-10%) and 33 V at high line (30 V+10%).

Figure 3

The output of (V) is 0 to 5 VDC or 10 VDC depending on model. As much
as 10 mA may be drawn from (V) without affecting accuracy. This limits
the minimum load RL connected to Vo to 1 KΩ or higher. Remember to
keep the wiring resistance between the output and the receiver RLlow
compared to value of RL. While the voltage at the terminals remains
unchanged with a 10 mA current flow, resistive losses in the wiring do
cause errors in the voltage delivered to RL. For a 1% accurate gauge, a
good rule of thumb would be to keep the resist 0.1% of the value of RL.
This will keep the error caused by current flow below 0.1%.

To minimize noise in the signal use shielded cable. The common line
may also be grounded.

Pressure Connections

Two integral tubing connectors are provided. They are designed to fit
3/16˝ (5 mm) ID tubing. Connect the high pressure to the High side as
shown in Fig. 4. Be sure the pressure ratings of the tubing exceed that
of the operating ranges.

POWER SUPPLY VOLTAGE

Figure 2

The maximum length of connecting wire between the transmitter and the
receiver is a function of wire size and receiver resistance. That portion of
the total current loop resistance represented by the resistance of the
connecting wires themselves should not exceed 10% of the receiver
resistance. For extremely long runs (over 1,000 feet), it is desirable to
select receivers with higher resistances in order to keep the size and cost

HIGH LOW

of the connecting leads as low as possible. In installations where the
connecting run is no more than 100 feet, connecting lead wire as small

Figure 4

as No. 22 Ga. can be used.

3-Wire Operation:

CAUTION

DO NOT EXCEED SPECIFIED SUPPLY
VOLTAGE RATINGS. PERMANENT DAMAGE

NOT COVERED BY WARRANTY WILL RESULT.