AW Gear Meters CAPM-3o User Manual

Technical Data

Supply Voltage: 10 to 30 Volt DC
Supply Current: 20 mA @ 15 Volt, Max 35 mA
Minimum Signal: 0.5 Hz
Signal Output: Square wave, V

High

≈ VCC - 1.5V

V

Low

≈ 0V

Duty Cycle: 50%
Frequency Output: Flow dependent, up to 2000 Hz
Load: >500Ω
Driving Capacity: 10 mA Max
Temperature Range: -60°F to 185°F (-50°C to 85°C)

Connections:
A – +10 to 30 Volt DC supply voltage
B – Ground for supply and signals
C – Frequency signal output

Note: If signal does not go to ground, connect
external resistor, 5 K-10 Kohm, between input and
ground of monitoring equipment.

Figure 1

AW Wiring Color Code:
Supply Voltage: Red
Ground: Black
Signal: White

CAPM-3o Carrier Frequency Pickup Module

Installation & Technical Guide

Installation:

• Ensure that the flow meter sensor cavity is free of debris prior to installation.

• Remove the lid from the CAPM-3o, use the 2 inner screws to attach the sensor to the meter and replace the lid.

Wiring should be installed by a qualified instrumentation technician.

Some basic installation guidelines are reviewed overleaf.

Description:

The CAPM-3o is a UL approved, intrinsically safe pickup sensor for use in Class 1, Div. 1 locations. The output
signal is a frequency proportional to flow in a square wave voltage form of approximate amplitude: Supply –

1.5V. The sensor must be installed with an intrinsic safety barrier in accordance with the guidelines detailed in
document # CAP2902 – CAPM INSTALLATION IN HAZARDOUS AREA. Recommended barriers such as
Pepperl & Fuchs Z787 (12-28V) are available from AW Gear Meters.

The output is a sourcing open collector transistor (NPN Type).

An NPN sinking type is available and is designated as CAPM-3i.

REV. 5/24/12 CAPM-3o.DOC

AW Gear Meters 8809 Industrial Drive, Franksville, WI 53126  web: www.awgearmeters.com

 Tel: [phone]  Fax: [phone]  Email: [e-mail]

Figure 2

Electrical Installation Tips for Sensors and Flow Meters

Wiring should be installed by a qualified electrician or instrumentation technician. When dealing with low
voltage/power signals from pickups and transmitters, it is important to use a shielded cable between the
transmitter and the signal processing unit. A shielded cable will keep most of the electromagnetic interference
(EMI) from entering the signal cable and disrupting the signal before it can be processed. A 20-22 gauge 3 or 4
conductor cable with shield is acceptable. Recommended cable: Belden #88723 2 pair stranded, 22 awg PTFE
coated cable. This cable is available from AW Gear Meters.

When hooking up to instrumentation, connect the shield together with the wire for the signal ground, to the

Instrument Ground terminal.

NEVER CONNECT THE SHIELD TO GROUND AT BOTH ENDS.

When hooking up to AW Flow Meters instrumentation, refer to the following drawing:

1. To prevent extraneous signal noise, ensure that a clean, central ground is established for both the flow
meter and sensor.

2. Where possible, keep the signal cable at least 1 foot from any cable handling 110 Volt AC. If several
signal cables are used, consider using metal conduit tubing for the signal cables for extra protection
and shield from external noise and EMI. If possible, ground the conduit at one end. Ground to a water
pipe or another good ground connection.

3. Place the pickup well away from motors, starters and relays. If used in a location where there are
starters and other controls using relays, be sure there are diodes mounted across the coils for DC
relays, and an R-C network for AC relays. This will dampen EMI from the relays when they operate.

4. Supply clean, regulated DC power with a ripple under 3% of supply

If the sensor appears faulty, review the following steps:

1. Detach the wiring connector from the sensor. Using a short wire, repeatedly touch pin A to C inside the
wiring connector. These simulated pulses should register at the instrument. If this does not occur, verify
that the wiring connections are set up as shown in Figure 2 above and check the instrument. If using a
non-AW instrument, check the specifications for signal compatibility.

2. If the pulses do register, re-attach the wiring connector to the sensor and rapidly move a screwdriver

back and forth 1/16” in front of the sensor nose. If pulses register, the sensor is okay. If not, contact the

factory for a return tracking number.

Note: If the sensor transmits a frequency irrespective of flow or by touch, the cable shielding and/or
grounding is faulty and the equipment is behaving as an antenna.

AW Gear Meters 8809 Industrial Drive, Franksville, WI 53126  web: www.awgearmeters.com

 Tel: [phone]  Fax: [phone]  Email: [e-mail]

REV. 5/24/12 CAPM-3o.DOC