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Split-Range Transmitter (Model: MFS)

This device is to generate two current signals from a single controller’s current output source for the purpose of split ranging control.

MFS

Features

Plug-in type construction

Main advantage is ease of installation and troubleshooting.

Two combination types of current output signals

Parallel and V-shape (inverse direction) characteristics can be chosen.

Control output monitor terminals

Outputs can be easily checked at any time via front panel jacks without disturbing output connections.

Minimizes DCS outputs to control final control elements

Expensive DCS output points can be reduced by 1/2.


The Model MFS Split-Range Transmitter is a signal conditioner that can be used to manipulate two control valves with only one input signal.
This type of function is usually obtained by using a valve positioner’s split ranging action.
However, by using the Model MFS, ordinary control valves that are configured for a 4 – 20 mA input can be used for this purpose.
As for the characteristics combination of two control output signals, V-shape (inverse) and parallel types are offered.
Either one can be used depending on the valve’s operating direction.
With a DCS, the number of control outputs can be reduced from two to one if the Model MFS is used.

The V-shape characteristics model (Model: MFS-V) is typically used when temperature is controlled by using hot and cold water, and either line valve has the same opening direction in relation to the input signal.
As an example, a cold water line valve is controlled from fully open to closed with the input signal range of 4 – 12 mA DC while the hot water line valve is controlled from closed to fully open with the input signal range of 12 – 20 mA DC (See Figure 1).

Figure 1. Operation of V-shape characteristics Split-Range Transmitter, Model MFS-V.
Figure 1.
Operation of V-shape characteristics
Split-Range Transmitter, Model MFS-V.

With the Model MFS-V, 0% (4 mA) on output signal No.2 can be adjusted over the input range of 10 – 20 mA DC.
In the same manner, 0% (4 mA) on output signal No.1 can be adjusted over the input range of 4 – 14 mA DC.
That is to say, the Model MFS provides the flexibility to adjust both outputs so that there is some overlap between them (See Figure 2).

Figure 2. OAdjustable range of V-shape characteristics Split-Range Transmitter, Model MFS-V.
Figure 2.
OAdjustable range of V-shape characteristics
Split-Range Transmitter, Model MFS-V.

The parallel characteristics model (Model: MFS-P) is typically used when temperature is controlled by using hot and cold water where these line valves have different opening directions in relation to their respective input signals.
For example, a cold water line valve is controlled from fully open to closed with the input signal range of 4 – 12 mA DC while the hot water line valve is controlled from closed to fully open with the input signal range of 12 – 20 mA DC (See Figure 3).

Figure 3. 
Operation of parallel characteristics Split-Range Transmitter, Model MFS-P.
Figure 3.
Operation of parallel characteristics
Split-Range Transmitter, Model MFS-P.

With the Model MFS-P, 100% (20 mA) on output signal No.2 can be adjusted over the input range of 10 – 20 mA DC.
In the same manner, 0% (4 mA) on output signal No.1 can be adjusted over the input range of 4 – 14 mA DC.
This shows that the Model MFS provides the flexibility to adjust both outputs so that there is some overlap between them (See Figure 4).

Figure 4. Adjustable range of parallel characteristics Split-Range Transmitter, Model MFS-P.
Figure 4.
Adjustable range of parallel characteristics
Split-Range Transmitter, Model MFS-P.

Applications