Dwyer Instruments PHOTOHELIC 3000 SGT series Specifications-installation And Operating Instructions

SERIES 3000 SGT PHOTOHELIC

SNAP RING GROOVE

Ø4-3/4 [120.65]

MOUNTING HOLE

1/8 NPT FEMALE PNEUMATIC TAPS

2-1/16
[52.39]

2

[50.80]

PANEL 5/8 [15.88] MAX

1-1/4

[31.75]

3/16

[4.76]

5/8

[15.88]

2-1/2

[63.50]

3-7/8

[98.43]

5-1/8

[130.18]

4-3/8

[111.13]

HOUSING REMOVAL

3/4 [19.05]

CONDUIT OPENING

Ø4-3/4
[120.65]
FLANGE

3-7/8
[98.43] SQ
HOUSING

Ø4

[101.60]

FACE

5

[127.00]

0.D.

BEZEL

5-1/2

[139.70]

O.D.

MOUNTING

RING

Northeast Controls Incorporated
P.O. Box 275 - Upper Saddle River, New Jersey 07458 USA
Tel: [phone] | Fax: [phone] | [e-mail]

®

Bulletin B-36A

DIFFERENTIAL PRESSURE SWITCH/GAGE TRANSMITTER

Specifications – Installation and Operating Instructions

Fig. A

The PHOTOHELIC®Series 3000 SGT is a versatile 3-in-1

instrument combining a time-proven Magnehelic
pressure gage, low/high limit pressure switches and a 4-20 mA
pressure transmitter. It is designed to measure and control pos­itive, negative or differential pressure of air or other non-com­bustible, non-corrosive gases. Gage reading is unaffected by
switch or transmitter operation. Switch set points are easily
adjusted with knobs located on gage face. Applied pressure and
switch set points are fully visible at all times. Deadband is one
pointer width, less than 1% of full scale. Each set point controls
a DPDT relay and both can be interlocked to provide variable
deadband control. The 2-wire transmitter operates indepen­dently, driven by a separate external 10-35 VDC power supply.
Separate zero and span potentiometers are provided inside the
rear electronics package for easy field adjustment.

PHYSICAL DATA

Ambient Temperature Range: 20 to 120˚F (-6.7to 49˚C)
Maximum Pressure: Model No’s. 3020SGT & 3030SGT —

11psi (75 kPa); all other units 5psi (35 kPa).

Accuracy: ±2% of full scale at 70˚F (21.1˚C) (3% on -0).
Pressure Connections: 1/8˝ NPT(F)
Case FInish: Baked dark gray epoxy enamel
Conduit Opening: 3/4˝
Standard Accessories: (2) 3/16˝ tubing to 1/8˝ NPT brass adapters for

rubber or vinyl tubing, (1) mounting ring. (1) snap ring, (4) 6-32 x 2˝
mounting screws, instructions
Compatibility: Use only with air or other non-combustible, non-corro­sive gases

Weight: 4lbs., 12oz. (2.15 kg)

ELECTRICAL SPECIFICATIONS (Switches)

Power Supply: 117 VAC
Current Consumption: 5 watts average
Contact Rating: 10A @ 24 VDC or 120 VAC, 6A @ 240 VAC.

ELECTRICAL SPECIFICATIONS (Transmitter)

Power Supply: 10.0 to 35 VDC
Output Signal: 4-20 mA DC, 2-wire (limited at 38 mA)
Loop Resistance: 0-1250 ohms
Current Consumption: 38 mA DC, maximum
Span and Zero Adjustment: Multi-turn potentiometers,

internally accessible

Thermal Errors: ±1% per 50˚F typical
Warm-up Time: 10 minutes

®

differential

INSTALLATION

1. Location: Select a clean, dry, vibration-free location where

ambient temperatures will be between 20 and 120˚F (-6.7
and 49˚C). Tubing supplying pressure to the instrument can
be practically any length but long runs will increase response
time slightly.

2. Position: The PHOTOHELIC
use with scale in a vertical plane. Operation at other angles
may affect accuracy and/or require zero adjustment. Most
models can be specially calibrated at the factory for other
positions if specified at time of ordering. Ranges below 1˝
w.c. must be used only with scale vertical.

3. Mounting: Normal mounting is flush or through panel as
shown in Fig. B. Allow 4-3/8˝ space behind the unit for elec­trical enclosure removal. Make 4-3/4˝ diameter hole in panel.
When installing multiple units, it may be preferred to obtain a
Model 730E, 120mm chassis punch as manufactured by
Greenlee Tool Co. and available from your machine tool dis­tributor.

Insert PHOTOHELIC

®

ing ring over the case from rear and seat the snap ring in its
groove. Thread the (4) 6-32x2˝ machine screws into mount­ing ring, back it against snap ring and tighten screws to back
of panel. An alternative to flush mounting is the optional A­371 Surface Mounting Bracket. Unit is mounted in this
bracket as described above and bracket is then surface
mounted. Contact factory for details.

®

SGT is factory calibrated for

unit from front of panel, slip the mount-

Fig. B

4. Zeroing & Pneumatic Connections: After unit is installed in

COVER MOUNTING
SCREWS

FLEXIBLE CONDUIT

SUPPORT CONDUIT
FROM PANEL

SECTION B

SECTION A

SECTION C

SECTION D

SECTION E

its final mounting position, use the screw at bottom of front
cover to adjust pointer for exact zero reading. This must be
done with both pressure ports open and vented to atmos­phere.

(A) For positive pressure, connect tubing to HIGH PRESSURE

port and vent LOW PRESSURE port to atmosphere.

(B)For negative pressure (vacuum), connect tubing to LOW

PRESSURE port and vent HIGH PRESSURE port to atmos­phere.

When either port will be left open to atmosphere, we suggest
installation of optional A-331 Filter Vent Plug to keep gage
interior clean.

(C) For differential pressure, connect higher pressure to HIGH

PRESSURE port and lower pressure to LOW PRESSURE
PORT.

NOTE: If the PHOTOHELIC

®

SGT is over-pressured beyond
its full scale range, pointer could jump from full scale back to
zero and remain there until the excess pressure condition is
relieved. Users should be aware that this condition would
cause a false indication of zero pressure and subsequently
affect set-points and transmitter output signal.

Section E (L1 and L2) contains power supply connections for
the control unit transformer primary. The transformer in turn
supplies reduced voltage power for the LED, phototransistor,
amplifier unit, load relay pull-in and holding coils.
Connections must always be made to this section for the unit
to operate. Standard units require 117 VAC but options are
available for other power sources. See label on terminal
board for correct voltage and circuit style.

CAUTION: Do not apply electrical current to ter-

minals in Sections B and C.

Fig. D

Separate Ground Wire attachment is provided for by a No.

6-32 screw on the mounting bracket near the conduit open­ing.

SWITCH/GAGE WIRING CONNECTIONS

To make electrical connections, remove the (3) cover screws
and slide cover off. All wiring should be fed through flexible con­duit attached to conduit opening at bottom of electrical pack­age. Conduit should be attached to the panel of other suitable
support to avoid excess strain on the instrument. See Fig. C.

Fig. C

1. Low/High Set-Point Wiring Connections

The rear terminal board contains connections for low and
high set-points, holding coil circuits and line power supply.
Transmitter connections are located behind this terminal
board. See TRANSMITTER WIRING CONNECTIONS for
complete information.

Section A contains DPDT connections for the right or high
set-point and Section D contains identical connections for
the left or low set-point.

Terminals in Section B are for control of the holding coil cir­cuit for the right, high set-point and Section C contains iden­tical connections for the left, low set-point. These holding
coil circuits are typically used to allow latching set-points
with manual reset or for adjustable deadband operation with
one set-point wired to reset the other. See paragraphs 3 and
4 for details. Do Not Connect Line Current to Sections B or C.

2

Single Set-Point instruments are furnished with the right or
high set-point components and circuitry in place. These are
connected to Sections A and B of the terminal board. The left
or low set-point components are omitted.

2. Circuit Style: The PHOTOHELIC

®

is available with several
factory installed optional internal circuits. They are identified
as to style by a label shown in Fig. E. This label is mounted
prominently on the terminal board of each instrument. The
letter H denotes a circuit in which the relay can be made to
latch or remain energized after pressure increase to its set­point.

The letter L denotes a circuit in which the relay can be made
to latch or remain de-energized after pressure decreases to
its set-point. Two letters are required to fully identify a dual
set-point. Two letters are required to fully identify a dual set­point unit. Thus, circuit style HH, which is standard, is a dual
set-point circuit which has provisions for latching on pre­sure increase to either set-point. Single relay units are iden­tified by the letters SR followed by H for the standard unit or
L for the special low latch unit. Units for use with other than
standard 117 VAC will be so indicated on the label.

Fig. E

3. Dual Set Point Automatic Reset: Circuit Style HH is used

for simple on-off switching applications. To place in service,
connect load circuits to the appropriate terminals in Section
A (Fig. D) for the right set-point and Section D for the left set­point. Note that the N.O. contacts are open when the gage
pressure pointer is to the left of the set-pointers. No connec­tions are necessary in Sections B and C. Make external
ground connections as required and connect power to
Section E for the control unit. To use circuit style LL for auto­matic reset, a jumper wire must be installed between the
upper and lower terminals in Sections B and/or C.