Emerson Fluid Chiller Anleitung zur Fehlerbehebung PDF herunterladen (Seite 23)

Emerson Climate Technologies

Electronic Valves & Controls

Emerson Climate Technologies

Function

Dip Switch Number

1 2 3 4 5 6 7 8

EX4/EX5/EX6 operation 0 1 1 0 1 0 – –

EX7 operation 1 0 0 1 0 1 – –

EX8 operation 1 1 0 1 1 1 – –

4-20 mA analogue input signal – – – – – – – 0

0-10V analogue input signal – – – – – – – 1

With start mode – – – – – – 1 –

Without start mode – – – – – – 0 –

Setting

The universal driver needs no setting except congu-

ration with dip-switches for the application of a different

valve, different analogue input signal, and type of start

mode.

Electrical Control Valve – EX

Function

1) Motor

A 2-phase bipolar stepper motor drives the

EX4/5/6/7/8. This motor follows the basic operating

characteristics of any stepper motor i.e. the motor will

be held in position unless current pulses from a driver

board initiate rotation in either direction.

3α 2α 1α

2 3 1

ime

Pulse

Angular rotation (cross section of shaft)

2) Valve

The gate type valve is optimized to provide a wide

range of capacity with a linear relation between ow and

positioning of the valve (capacity vs. number of steps).

Slide and ports are made from ceramic for precise ow

characteristics, high resolution and innite life.

The compliant slide eliminates undesirable horizontal

forces caused by differential pressure (across the valve)

to the cage assembly and shaft of stepper motor. The

internal design of the EX4/5/6/7/8 is patented.

Total valve travel is 750 full steps for EX4/5/6, 1600

steps for EX7 and 2600 steps for EX8.

A mechanical stop in the fully closed position of the

valve acts as reference point. The controller is reset

by driving the valve towards the fully closed position

against the mechanical stop. By overdriving the valve

i.e. applying more than the full number of steps, it can

be assured that the reference point is correct.

closed

open

The direction of the rotation depends on the phase

relationship of the current pulses, the amount of rota-

tion is dependent on the number of pulses. One pulse

will drive the motor one step i.e. the rotor will move

by a=1.8°. Successive pulses will lead to continuous

rotation.

The drive shaft of the rotor is connected to a spindle

which transforms the rotation into linear motion of the

valve slide.

Third Party Controller

The EXD-U driver simply converts a 4-20ma/0-10

volt signal directly proportional to the valves position of

0-100%, a third party controller is required to supply the

input signal to the EXD-U00.

The third party controller is typically a programmable,

stand alone set point control. It would contain built-in

PID control or algorithms capable of being tuned and

modied to achieve optimum control of the controlled

medium. This signal could also originate from a BAS

(building automation system), EMCS (energy manage-

ment control system) or industrial process controller

as long as the signal type is compatible and the proper

programming capabilities are available.

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