AZEL SINGLE STAGE User Manual
DST-777S, DST-777D
SETPOINT TEMPERATURE CONTROLS
INSTALLATION AND OPERATING INSTRUCTIONS
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TECHNOLOGIES
ZEL
ZEL
APPLICATION
DST-777 series controls are microprocessor-based electronic
one or two stage setpoint temperature controls, designed to provide
one or two on/off controls (Single-Pole Double-Throw(SPDT) relay
outputs) for residential/commercial heating, cooling, air conditioning
and refrigeration applications.
The DST-777 is equipped with a Dual Digital display with backlit
that provides a constant readout of the sensor temperature and
setpoint simultaneously as well as the other programmed settings. The
front buttons allow the user to easily and accurately select the setpoint
temperature, differential and heating/cooling mode of the operation.
Unique feature allows instant setpoint adjustment without
entering programming mode. This reliable and versatile control has a
very wide setpoint range, an adjustable differential and time delay that
makes it applicable in many different applications. The single stage
models have Pulse Width Modulation (PWM) control logic to prevent
overshoots and undershoots in slow responding systems with large
thermal mass such as pools or slabs. A sensor probe P-01 is supplied
with the control. This solid state temperature sensor probe can be
extended up to 500 feet.
QuickSet
FEATURES
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Reliable Digital ElectronicAccuracy
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QuickSet
entering programming mode
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Easy-to-Read Dual Digital Display with backlit which provides
constant readout of sensor temperature and setpoint
simultaneously, functional status and control settings. It also
allows precise setpoint and differential settings
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Simple and user-friendly programming of setpoint
temperature, differential and cooling/heating modes
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EEPROM memory retains control settings in the event of a
power failure
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Wide adjustable setpoint with temperature range from -40 to
240°F and differential from 1 to 100°F. This enables the user to
optimize the system performance for any applications. A
tighter differential can be achieved (eg. 1°F or 1°C) than
conventional electromechanical controls
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Advanced PWM (Pulse Width Modulation) Control to achieve
high control accuracy on single stage models
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Choice of one or two stage models
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One or two SPDT relay outputs. Model: DST-7772(two stage)
can handle one or two sensor inputs with two setpoints. When
using two sensor inputs, each setpoint can be corresponding
to one relay output. (Twounits in one control)
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LED indicates output relay status
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Adjustable Anti-Short Cycle Delay to ensure the output relay
remains off for up to 20 minutes. This would avoid
unnecessary hard start and equipment wear
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Selectable Fahrenheit or Celsius scales
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Selectable Heat or Cool modes
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Maximum and minimum memory for sensor temperature
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Lockout mode to prevent tempering by unauthorized
personnel
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Remote temperature sensor which can be extended to 500 ft.
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Sensor failure and out of range indication
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Easy installation and setup
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Fast sampling rate (1 sec.) Of the sensor temperature for
instant control action
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Easy-Connect Screwless Terminals for sensor connection
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Backlit option:Auto(30sec.)/OFF/ON
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Power surge protection
feature allows instant setpoint adjustment without
SPECIFICATIONS
Setpoint Temperature Range: -40 to 240°F(-40 to 116°C)
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Temperature Display Resolution: 0.1°F/0.1°C
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Differential Adjustment: 1 to 100°F(1 to 38°C)
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Anti-Short Cycle Delay: 0 to 20 min. (1-Minute increments)
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PWM Cycle Length: 30 to 1500 sec. (10-Second
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Increments)
PWM Differential: 3 to 50°F (2 to 25°C)
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Accuracy: ±1°C / ±1°F
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Input: 10K ohm thermistor probe(included): P-01 (designed
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for strap on a pipe or insert into a temperature well)
Temperature sampling rate: 1 second
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Operating Voltage: 120 or 240 VAC, 50/60Hz
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Relay: 1 or 2 x SPDT, 120VAC, Full Load 16A, 1Hp
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Enclosure: Flame Retardant Plastic 94V0
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Weight: 3.0 lbs
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Dimension:
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P-01 Sensor Probe:
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Sheath: Copper
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Lead: 10” of 20 AWG heat resistence wire
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Dimension: 3/8" OD x 13/16" length
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Operating range: -60 to 255 F (-50 to 125 C)
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Sensor: 10K ohm @ 77 F (25 C ± 1%) thermistor
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Can be strapped on a pipe or inserted into a temperature well
Models:
DST-777S Single Stage Setpoint Temperature Control
DST-777D Single Stage Setpoint Temperature Control with 2 outputs
6 3/8”(W) x 6 5/8”(H) x 2 3/4”(D)
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CAUTION!
1. To prevent electrical shock hazard, disconnect power supply before
installing.
2. All wiring must comply with national and local electrical codes,
ordinances, and regulations.
Never connect the load terminals to a load that takes more current than
the amount listed for therelay in the electrical ratings.
3. Azel Technologies is not responsible for damages resulting from misuse
of its products.
4. 12-18 gauge wire isrecommended for 120 VAC conections;
18 or larger wire is recommendedfor sensor connections.
gauge
5. This literatureis providedfor informational purposes only.
MOUNTING
Mount the DST-777 controller to a suitable surface. Slotted keyholes and
standard holes areprovidedfor mounting purposes.
MOUNTING THE SENSOR:
The sensor P-01 can be extended up to 500 with conventional 18 gauge
wire(or larger to keep additional resistance to a minimum). It is designed to
strap on a pipe orinsert onto a temperature immersion well.
Senors should be strapped to the pipe with cable tie. The flat side of the
sensor should be resting on the pipe. In addition, they should be covered with
a layer of insulation to minimize the effects of ambient temperature for a more
reliable temperature reading.
The sensor P-01 can also be insert onto a 3/8”(10mm) or ½”(12.7mm)
ID temperature well.
Note: Do not run sensor wires parallel to other electrical wiring or telephone
wires. In case there is strong source of electromagnetic interference,
twisted pair 20AWGwire is recommended.
ROUGH-IN WIRING
Loosen the screws on the top and bottom of the enclosure and remove the wiring
covers by swinging them away from the base(grey color) with the edges of the
covers as pivot(see Figure 1).
The base has standard 7/8” (22mm) knockouts which accept common wiring
hardware and conduit fittings. Before removing the knockouts, check the wiring
diagrams and use the chamberwith common voltages.
Side view
Figure 1
OPERATION
Liquid Crystal Display
In normal operating mode, the upper LCD display the current sensor temperature
and thelower LCD display the setpoint temperature. The display is also used with
the Up Arrow and Down Arrow buttons to adjust the setpoint temperature,
differential and heating/cooling modes ofthe operation.
LCD Blue Backlit Options: set by slide switch on the front panel
ON - backlit is turned on.
OFF - backlit is turned off.
Auto - backlit is turned on for 30 secs when any button is pressed.
L.E.D. SYSTEM STATUS INDICATION LIGHTS:
RED light indicates that theSPDT relay output is energized.
Heating Mode and Cooling Mode:
set by keypad
Normal Control Mode(ON/OFF Control): SetPWM slide switch to OFF
The control outputs will turn on the equipment when there is a demand for
heating or cooling. When the demand is satisfied, the control outputs will turn
it off.
Pulse Width Modulation (PWM) Mode(PWM CONTROL): Set PWM slide
switch to ON
The single stage models (DST-777S, DST-777D) offer optimum control by
means of a Pulse Width Modulation(PWM). In PWM, the ON and OFF cycle
vary depending on the difference between the sensor and setpoint
temperature. The bigger difference between the sensor and setpoint
temperature, the longer the relay is switched ON. When the sensor
temperature approaches the setpoint temperature, the ON time become
shorter and shorter. Pulse Width Modulation guarantees precise control
response. This function prevents overshoots and undershoots in systems
with large thermal mass (eg.slabs or pools).
Figure 3 shows the operationof relay on Heating Mode duringPWM cycle:
If the sensor temperature is half of the PWM Differential above the
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setpoint temperature (in this exampleis: 79°
If the sensor temperature is half of the PWM Differential below the
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setpoint temperature (in this exampleis: 71 F (75 - 8/2),relay is ON.
If the sensor temperature is between 71 F and 79 F , PWM is in action.
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F (75 + 8/2), relayis OFF.
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When the sensor temperature crosses the rising slope of the triangle
wave generated by the control, relay is turned ON during the shaded
region. When the sensor temperature passes the falling slope of the
triangle wave, the relay isturned OFF during the unshaded region.
The pulse width (the relay ON time within one cycle) is modulated in
!
according to how far the sensor temperature deviates from the setpoint
temperature.
If sensor temperatureis the same as the setpoint temperature, the pulse
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width is half (50%) ofthe cycle length.
If the sensor temperature is higher than the setpoint temperature, the
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pulse width allows shorter periodof ON time
If the sensor temperature is lower than the setpoint temperature, the
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pulse width allows longer periodof ON time.
If PWM mode is selected,the minimum time delay is disabled.
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The principle of operation on Cooling Mode is the same with the shaded
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and white area reversed inFigure 3.
Heating Mode
(factory setting):
The control output will turn on when the sensor temperature falls to the setpoint
temperature minus the differential amount. The control output will turn off when the
sensor temperature reaches the setpoint temperature. For example, if setpoint =
68F, Differential =3F, then output is on at65F and off at 68F.In other words, when the
heating mode is chosen, the differential is below the setpoint. The relay will deenergize as the temperature risesto the setpoint. Refer to Figure2.
Cooling Mode
:
The control output will turn on when the sensor temperature rises to the setpoint
temperature plus the differential amount. The control output will turn off when the
sensor temperature reaches the setpoint temperature. For example, if setpoint =
75F, Differential = 2F, then output is on at 77F and off at 75F. In other words, when
cooling mode is chosen, the differential is above the setpoint. The relay will deenergize as the temperature fallsto the setpoint.
The control output turned onmeans:
From the isolated SPDT relay output, “NO” are normally open contacts which close
and “NC” are normally closedcontacts which open when thecontrol output is on.
Temperature
+
Cooling
Mode
Setpoint
-
Figure 2: Operation of relay in according to Setpoint and Differential
Settings for both Heating and Cooling Mode
ON (relay energized)
OFF
(relay de-energized)
OFF
ON
Heating
Mode
Grey Area = ON region White Area = OFF region
Temperature
79 F°
Setpoint
=75F°
71 F°
Relay turned On
(Pulse width)
Figure 3: Operation of relay on heat mode during Pulse Width Modulation(PWM) cycle
Relay Turned Off
PWM Cycle Length
Sensor Temperature Curve
PWM Differential
=8 F°
Time
Anti-Short Cycle Delay: set by keypad
Anti-Short Cycle Delay can be set to ensure the output relay remains off for up
to 20 minutes (default is 0 mins) after relay is de-energized. This is adjustable
from 0 to 20 min with 1 minute increments. In other words, this function
establishes the minimum time that the output relay remains de-energized
before the next on-cycle. It does not allow the output relay to re-energize until
the programmed time delay has elapsed. The delay is activated when the
control is first turned on, but can be skipped within the first 3 seconds by
pressing the “SET” key onceand go to normal operating mode (Note:SET key
at this stage will not perform any other function except terminating the time
delay).
Anti-Short Cycle Delay is available only whenPWM is off .
When the delay is activated, the Upper LCD shows the current temperature
and the lower LCD shows blinking “AC” which stands forAnti-Cycle. Also, in
case there is a demand forheating/cooling, the red LED for relay outputwill be
blinking indicating that anti-cycle featureprevent relay from energizing.
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