Utility Switching Remote Control
An Android Mobile Phone App is used to set up the control unit, which then works independently until its operational commands are changed again by the phone app. If not overridden by control sensors, the output switching can be controlled by tapping pushbuttons on the mobile phone screen. The state of the output control is indicated on the mobile's screen.
The Utility Switching control unit can selectively supply power to an electrical device, typically a pump, or a heating/cooling appliance based on temperature, pressure or contents level parameters.
Temperature is measured by a digital probe with a range from -55°C to 125°C. An upper and lower limit is entered. A refrigerating device will work until the lower limit is reached, a heating device will switch of when the upper temperature is attained.
Fluid level is measured by an ultrasonic scanner set in the roof of the tank. Maximum tank depth is 2 metres. The pump can keep the tank filled by engaging when the lowest programmed point is reached until the tank is full according to the specified upper limit, or it can initiate an emptying phase when the upper limit indicates a full tank. The pump will then remain engaged until the lower limit setting is measured by the scanner.
When a pressure transducer is installed (100kPa, 300kPa or 700kPa) the control unit can switch a pump or compressor to drive the pressure up to the upper limit, starting when the lower threshold is crossed, or it can operate a relief valve to open at the upper threshold and stay open until the lower specified pressure is attained.
Additionally there is a momentary-contact button to energise a second relay that is enabled when the controller output is latched. This has been used for the purpose of, for instance, engaging the starter motor on a generator once the generator is enabled by the main relay.
Switching According to Temperature
When the controller detects that an optional digital thermometer is connected it will automatically start switching the main output relay according to the temperature input and the pre-set upper and lower limits.
The upper and lower temperature thresholds are easily set on the mobile phone and transmitted to the remote controller for storage in its non-volatile memory. Values between -55 and 128 deg. C are valid. The unit can be programmed for either heating or cooling - when in cooling mode it will switch on when the upper limit is reached and remain so to the lower limit, when heating it will switch on at the lower limit and maintain that state until the upper threshold is reached.
In both modes the output will switch off if contact with the thermal probe is lost. Temperature control takes precedence over manual control and other modes are disabled as long as the presence of the digital thermometer is detected.
Switching Controlled by Timer
There is a facility to program an 'On' time followed by an 'Off' time that the Remote Control will follow whether connected to the mobile or not. Both intervals are specified in seconds from 1 to 1 million. The manual 'On' control will override the timer. When manual control is relinquished the automatic timer will resume functioning as before.
To programme the timers the Remote Control must be BT connected to the mobile with Buttons Disabled. Tap the DactylTech logo 3 or more times in quick succession and the screen at right will appear. Edit the ON and OFF times (in seconds) and tap Send. The values are saved in non-volatile memory in the Remote Control. Timer control carries the lowest precedence, behind Temperature and Manual.
Switching to Maintain a Tank Level Limits
An ultrasonic scanner is mounted in the roof of the tank. The upper and lower level limits are set on the mobile phone as well as the command to either fill the tank or empty it. The control unit will switch the pump on and off so as to keep the tank level between the specified limits.
Switching to Maintain Pressure Limits
The control unit switches power to a pump or a relief valve to maintain the pressure in a vessel between the specified limits.
Pressure sensors are available with a full scale deflection (FSD) of either 100kPa, 300kPa or 700kPa. This translates into a water head of 10, 30 and 70 metres respectively (the height difference between the pressure sensor and the top of the tank). If a tank is 2 metres tall the pressure in the outlet pipe will vary by 20kPa between tank full and tank empty.
The minimum resolution of measurement is 0,1% of FSD, so a change of as little as 10m, 30mm or 70mm respectively can be detected. This allows the pressure in the discharge pipe to be monitored at a distance from the tank while the level in the tank can still be accurately assessed, which may remove the need to provide wiring to the tank.
If the tank is filled through the outlet pipe then measurements made while the pump is active will not be accurate. Under these circumstances a timer can be started when the low pressure limit is reached that will energise the pump for a pre-determined time before the next measurement is made, after which a new cycle is started
The control unit can monitor the state of a flow sensor placed in the overflow channel and switch off the pump as soon as an overflow condition is detected. This condition is reset at the start of the next ON cycle. Overflow detection is in place regardless of the main mode of detection, whether it be temperature, level, or pressure.
The current state of the output can be overridden by the Manual Control buttons only while the metered condition is within the operational limits. Once outside of those limits the controlling device - temperature, pressure, or level detector, will exercise a higher level of control.
The sensors can be disabled by setting both the HIGH and LOW limits to the same number.
After setting both the HIGH and LOW limits to the same number only the Timer and Manual Control will be operational.
To disable Timer Control set the On Seconds parameter to '0'.
Overflow detection is inhibited when both the sensor and the timer are disabled.