WIRING AND CALIBRATION

4-Wire Transmitter

Table

of

Contents

1. Installation and Wiring.......................................................................... 1
  1.1  General............................................................................................ 1
  1.2  Precaution........................................................................................ 1
2. Interfacing the Frequency Output.......................................................... 2
3. Interfacing the Limit Switches............................................................... 2
4. Field Calibration (4-20mA dc Output)..................................................... 3
5. Field Calibration (0-1000 Hz Output)...................................................... 4
     
Figure 1 Terminal Strip....................................................................................... 1
Figure 2 K-Factor Table....................................................................................... 2
Figure 3 Transmitter Connections........................................................................ 3
Figure 4 Transmitter Board.................................................................................. 4
1.1    General

The transmitter board is fitted inside the enclosure of either the threaded or wafer style flow meter. Option W provides a 4-20mA dc output signal, option Y provides a 0-1000 Hz frequency output signal, option X provides set point switching and option Z combines W, X, & Y.

The position of the pointer is detected using a pair of magnets mounted on the lever and a solid state Hall effect sensor mounted on the circuit board. The output of the transmitter is linear with flow. The transmitter is powered by an external 24 VDC power supply provided by the user. A rated capacity of 100mA is required to power all options.

1.2    Precautions

The power supply used to power the transmitter MUST BE ISOLATED. This means that the power supply ground and input signal ground must NOT be common. Some batch controllers and counter have auxiliary power supplies which are not isolated. Use of these non-isolated power supplies will cause failure of the power supply and/or transmitter board.

1.

Installation

&

Wiring

Important. Do not connect terminals 7 and 9 together. Damage will result. The installation must be 4-wire. One pair of wires supplies 24 Vdc to pins 7 and 8 and one pair carries the 4-20 mA signal to the peripherals. Click here for 4-20mA output to flow or flow to output calculator.

Terminal Strip

Figure 1

 

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2.1    Frequency Output Interfacing

The frequency output is always factory set to 1000 Hz at full scale flow. To count total flow from the frequency output, it is necessary to scale this output. Click here for frequency calculator. The scaling factor, K is derived as follows:

2.

Interfacing

the

Frequency

Output

  K =     1000 pulses / sec x 60 sec / min

             full scale flow rate (units / min)

The table below was computed from the above equation and is presented for your convenience.
Scale K-factor Scale K-factor Scale K-factor Scale K-factor
1 60000 20 3000 120 500 600 100
2 30000 25 2400 150 400 800 75
3 20000 30 2000 200 300 1000 60
4 15000 40 1500 240 250 2000 30
6 10000 50 1200 250 240 3000 20
8 7500 60 1000 300 200 4000 15
10 6000 80 750 400 150 6000 10
15 4000 100 600 500 120    

K-Factor Table

Figure 2

 

The frequency output is a square wave with an amplitude of 5 Vp (into a 10 K ohm or greater impedance). The on time is controlled at 270 microseconds ± 30 microseconds.

The frequency output falls to 0 Hz whenever the flow rate falls below approximately 20% F.S.

Important: Do not connect terminals 6 and 7 together. Damage will result.

The installation must be 4-wire. One pair of wires supplies 24 V dc to pins 7 and 8 and one pair of wires carries the frequency signal to the peripherals. If the current option is fitted, an additional pair of wires is required to carry the current output.

3.1    Limit Switch Interfacing

Power is required to the transmitter board in order for limit switches to operate. When no power is available, both switches are open and do not close regardless of the flow rate.

  • LO Switch    When power is applied at zero flow, the LO switch closes. As flow increa-                     ses to the set point, the LO switch opens.

  • HI Switch    When power is applied at zero flow, the HI switch remains open. As flow In-                   creases to the set point, the HI switch closes.

Each switch can be independently set to anywhere in the flow range. Therefore, the terminology of HI or LO is purely arbitrary. The user can achieve the desired fail safe system wiring by reversing the convention if necessary. As a result the relays can be wired to suit most system or alarm applications.

3.

Interfacing

the Limit

Switches

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NOTE: ALL GROUNDS, + 24Vdc in, 4-20mA, frequency output MUST be isolated from each other.

Transmitter Connections

Figure 3

Field

Calibration

(4-20mA dc)

 
 
   
4.1    Test Equipment

Fluke 9600A digital multimeter or equivalent and a Non-metallic screwdriver.

4.2    Setup

Remove the back cover plate to gain access to the adjustment pots and mechanical parts of the flow meter. (Refer to the installation, Operation and Maintenance Manual M1 for additional mechanical adjustments if necessary. Remove the lens to gain access to the pointer. Make all mechanical adjustments to the flow meter before proceeding.

DO NOT APPLY POWER UNTIL ALL CONNECTION ARE MADE.

Connect 24V dc power supply positive to terminal 8 and negative to terminal 7. Set multimeter to milliamp scale and connect to terminal 9 and 10. turn power ON. Observe current output reading. Click here for calibration video clip.

4.
 
   
4.

Field

Calibration

(4-20mA dc)

4.3    Adjustment Pot Location

Pots VR1, VR2 and VR3 are located just to the right of the terminal strip when viewing the flow meter from the rear. VR1 is adjacent to terminal 10, VR2 is the center pot and VR3 is the rightmost. See Figure 4.

4.4    Calibration

Note: The easiest way to set the pointer for calibration of the transmitter is with the vertical lever. By manipulating this lever, the pointer can be driven up/down scale to the desired location., simulating the flow rate at any given point. (Take care not to flex or push forward the lever as calibration will be affected). Click here for 4-20mA calibration video clip.

Adjust zero pot VR1 fully CCW. Adjust 4mA output pot VR2 to 4.00mA. Set pointer to 30% using the lever or flow. Adjust zero pot VR1 to 8.6mA. Set pointer to 95%. Adjust span pot VR3 to 19.2mA. Repeat zero (VR1) and span (VR3) adjustment until both adjust within specifications.

5.1    Field Calibration

If the transmitter is fitted with current output, adjust current output first. With the pointer at 95% F.S. set VR6 pot to 950 Hz ± 30 Hz. If current output is not fitted, the flow meter MUST be returned to the factory for calibration.

Important: When making adjustments to VR3 take care not to push on the Hall effect sensor as this will affect the calibration or cause damage.

Calibration is now complete remove the multimeter, re-connect the wires to each peripheral and reinstall the back cover plate.

5.

Field

Calibration

(0-1000 Hz)

Transmitter Board

Figure 4

M2 Rev D Wiring and Calibration Options W, X, Y & Z
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