Description
This Tech Note describes how the Observant C3 Platform can be used to control a DC Motor Pump or an AC Induction Motor Pump with a latching relay. The connection of a C3 to an electric motor according to this Technical Note should only be performed by an experienced electrician. Remote control capability should not replace local on/off control or any other fail-safe hardware. An Emergency Stop button and appropriate power disconnects should always be in place at the same location as the motor.
Application
A Latching Relay should be used to control a pump if the pump needs to be on for greater than 3 hours a day and the Field Unit is powered via a solar panel. This is because this configuration requires only short pulses from the C3 to operate and will not adversely affect a Field Unit's battery health.
Safety Disclaimer
On-site installation including starter (if applicable), drive (if applicable), contactor, emergency stop and appropriate fail-safe circuits will not be provided by Observant. Observant C3 will interface with 12 VDC relay for on-off control.
Pump must be installed by a qualified electrician and/or mechanic. The connection of a C3 to an electric motor should only be performed by an experienced electrician. Fail-safe circuits must be included that are appropriate for remote operation. Remote monitoring and/or control through the Observant platform does not constitute or replace hard-wired safety shutoffs. An Emergency Stop button and appropriate power disconnects should always be in place at the same location as the motor.
Supported Hardware
Electrical motor contactors are typically controlled by high-voltage AC supplies. These need to be controlled by the nominal 12 VDC outputs of the C3 by using 12 VDC coil, mains-rated, contact relays.
Recommended latching relays include:
- Releco Plug In Latching Power Relay, 12V DC Coil C9-R21
- IDEC RR2KP-U DC12
Contact our Support Team for the relevant Part Number if you'd like to order latching relays from us.
Installation
- It is typical for the C3 and associated wiring to be housed within the same switch box as the electric pump contactor.
- Both the C3 and the relay(s) can be mounted on standard, 25 mm DIN rail.
- All existing safety components including disconnects, fuses, overload protection and emergency stops should be left in place without modification.
In this configuration, the C3 uses two outputs to control a latching relay:
- Wire Output 1 of the C3 across the Set terminals of the relay
- Wire Output 2 of the C3 across the Reset terminals of the relay
Below are example wiring diagrams.
Releco Relay
For the Releco C9-R21 / DC 12 V, Output 1 is wired to ON terminal 13, Output 2 is wired to OFF terminal 10, and GNDs are wired to terminal 14.
IDEC RR2KP-U DC12
For the IDEC RR2KP-U DC12 relay, Output 1 is wired across Set terminals 10 and 2. Output 2 is wired across Reset terminals 6 and 3.
Omron MY2K
Output 1 is wired across Set terminals 14 and 13. Output 2 is wired across Reset terminals 12 and 9.
Feedback
It is highly recommended to incorporate feedback into the C3 to monitor whether the pump actually turns on. Flow switches and/or pressure switches can be connected to the C3's Dual-Purpose Digital/Analog Inputs to monitor pump intake and output. At a minimum, wire the pump status into an Input port of the C3. For installation details and specifications refer to: Technical Note — Switched Input to Monitor Equipment State
Configuration
This setup corresponds to the 'Electric Pump Controller' device in Global. This can be found under the 'Pump Control' category in Manage Equipment. If water flow is being monitored with a flow switch or pressure switch, choose the Input port that is monitoring the flow. Otherwise leave it as None. You can also feedback the pump status through an Input port if you're not monitoring flow.
The pump will be shut off automatically if there is no flow for the duration in the Timeout field. An alert will be sent if you are registered for alerts.
Note - a pulse output flow meter cannot be used as a flow indicator at this stage.
To set up pump automation, contact our Support Team.