Ashcroft A4 Instructieblad - Pagina 2

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A4 INTRINSICALLY SAFE &

NON-INCENDIVE RATED PRESSURE

TRANSMITTER INSTRUCTION SHEET

Mounting

The A4 transmitter requires no special

mounting hardware, and can be mounted in

any plane with negligible position error.

Although the unit can withstand normal

vibration without damage or significant

output effects, it is always good practice to

mount the transducer where there is mini-

mum vibration.

For units with NPT type pressure fittings

apply Teflon

tape or an equivalent sealant

to the threads before installing.

When tightening, apply a wrench to the

hex wrench flats located just above the

pressure fitting. DO NOT tighten by using a

pipe wrench on the housing.

Power Supply

Power Supply Voltage

Output Signal

Min

4-20mA*

12V**

* Refer to Ashcroft drawing #825A022 for

supply voltage and load limit.

** The minimum voltage at the terminals is

12Vdc. However, the minimum supply

voltage should be calculated using the

following graph and formula.

Loop Supply Voltage vs. Loop Resistance

1000

30 Vdc max for

Intrinsically Safe

800

Installations

600

400

Operating

Region

200

Loop Supply Voltage (Vdc)

Vmin = 12V+ (.022A x RL) (includes a 10% safety factor)

RL = RS + RW

RL = Loop Resistance (ohms)

RS = Sense Resistance (ohms)

RW = Wire Resistance (ohms)

All sales subject to standard terms and conditions of sale. A4_transducer_im_ RevB_(009-10166)_09-18

Noise

For minimum noise susceptibility, avoid

running the transducer's cable in a con-

duit that contains high current AC power

cables. Where possible avoid running the

cable near inductive equipment.

Shielded Cable

Units with shielded cable electrical ter-

mination, connect the drain wire to the

guard terminal on the read out device or

measuring instrument, if available. In all

other cases connect to the ground or to the

power supply negative terminal.

Vent Tube (Cable Termination Only)

The cable has a clear Teflon

required at pressure ranges below 500

psi to provide atmospheric reference. The

open end should be placed in a

dry area.

Max

A4 Wiring Diagrams

30V

POWER

SUPPLY

–

METER

OR OTHER DEVICE

A4 transducer has internal transient

protection: for safety, limit line-to-

ground voltage to 36 Vdc max.

Zero and Span Adjustment

Instructions below apply to the particular

configurations noted. While Zero adjustment

is not normally necessary, it may be desir-

able to trim out any offset in the system.

However, proper Span calibration requires a

pressure standard three to five times more

accurate than the accuracy of the trans-

ducer, and there may also be interaction of

Span on Zero.

vent tube

(+)

PIN 1

V+

TRANSDUCER

(–)

PIN 2

V–

4-20mA

A4 configurations with enclosure "S"

offer Zero and Span potentiometer

access.

Access to "Z" and "S" pots via the top

(electrical termination end) of the unit is

standard on all "S" enclosure units with

4-20mA output. Access is gained by

removing the black threaded cap, once

removed you will see the pots indicated

by "Z" and "S" respectively as shown

below. Using a small trim pot tool, you

can adjust zero ±10% of full scale and

span ±10% of full scale.

Z S

"Z" and "S" pots

Recalibration Instructions:

1. Apply 0% full scale pressure.

2. Adjust the output using the zero adjust

trim pot.

3. Apply 100% full scale pressure.

4. Adjust the output using the span

adjustment trim pot.

5. Repeat steps 1 through 4 as necessary.

HAZARDOUS AREA CERTIFICATIONS

Intrinsically Safe (applies to 4-20mA) FM/CSA:

Intrinsic Safety: Class I, II and III Div.1 and 2,

Groups A, B, C, D, F and G per

entity requirements see Ashcroft

drawing # 825A022

Non-Incendive: Class I, II and III Div. 2,

Groups A, B, C, D, F and G,

no barriers needed