Badger Meter Series 4000 Sensor - 1/2, 3/4", 1" - Manual (Page 17)

TROUBLESHOOTING
General
Primary consideration for troubleshooting a Series 4000 flow sensor is to first establish that the problem lies with the sensor
and not with the electronic device connected to it. A simple way to help determine this is to substitute a known working
sensor for the suspect unit. If the electronics react in an appropriate manner, you may conclude that the problem is sensor
related. Another option would be to provide a similar, square wave pulse simulation by hooking up a frequency generator to
the interface electronics and simulating as close as possible the actual sensor signal.
If you suspect a sensor problem, there are a few mechanical considerations to be addressed:
1. Make sure there is flow in the pipe line appropriate to the operations range (0.25-20 feet/second) of the sensor.
2. Make sure that the wiring between the sensor and the electronics is correct. If a junction box has been added, also make
sure that all wiring connections are right.
3. Check the impeller assembly to make sure it is not mounted in the reverse direction of flow.
4. Make sure that the impeller can spin freely on the shaft and that no foreign matter of debris has lodged in the sensor
housing.
TROUBLESHOOTING THE SENSOR
Digital Circuit
A sensor is a powered device, required voltage between 8VDC and 20 VDC, applied between the red (+) and black (-) sensor
leads. The sensor will normally draw about 1mA for this supply. WARNING: DO NOT EXCEED 20 VDC; SENSOR DAMAGE
MAY RESULT.
1. The white sensor wire should be disconnected. Make sure that the black, red and shield wires remain connected to the
proper terminals.
2. Install a voltmeter, positive (+) to the white sensor wire and negative (-) to the black sensor wire. If flow exists, you
should see a square wave switching between 0.0 VDC (low) and 4.0 VDC (high). NOTE: The pulse may be too fast for the
voltmeter to recognize as a square wave, but it may appear as an unstable reading somewhere between 2.0 and 4.9 VDC.
If flow is stopped, the output will hold in either a high (4.0 VDC) state or low (0.0 VDC) state, depending on the position of
the impeller reflector or other factors. To simulate impeller rotation, simply pass a metal object (i.e. large screwdriver or
pliers) past the back of the sensor. The output signal should then switch states.
3. If the sensor produces pulses in the above tests, reconnect the white sensor wire to the signal input terminal of the
transmitter. With the voltmeter still connected, note the actual voltage levels between the output switching (such as 0.0
VDC low or 4.0 VDC high). If reconnecting the sensor to the transmitter either stops or significantly alters the voltage
levels of the pulses, or if the transmitter does not respond to the pulses, consult the factory or your local representative.
4. A nonworking sensor could be the result of either a sensing coil failure or a component failure in the electronic module
(blue cover). Using an ohm meter, determine the coil resistance by removing the blue electronics cover containing the
encapsulated circuitry. Unplug the coil from the electronics in the cover. Connect the probes of the ohm meter to the
wire terminals of the coil plug-in connector. The coil resistance should measure between 5 and 10 Ohms. A very low or
very high resistance reading may indicate failed coil; if this appears, replace the coil.
5. If the coil appears to be within specification, replace the blue cover assembly from another working device. If the sensor
begins working, replace the electronic assembly.
6. If the sensor switches states when a metal object is passed near the back of the sensor, but no pulse occurs when flow
exists, verify that the flow meets our minimum flow requirements for the sensor. Check further the condition of the
impeller and the shaft for mechanical wear or damage. If replacement is necessary, a repair kit is available containing the
appropriate components.
Installation & Operation Manual
Page 17 April 2012