This article applies to contactor-controlled, single-speed motors only.
It is not intended as a reference for motors controlled by Variable Frequency Drives (VFDs).
All equipment exceeding the relay current rating must be controlled using a properly rated contactor.
Failure to do so may result in equipment damage, relay failure, or unsafe operating conditions.
Overview
The Attendant does not directly switch or power 3-phase motors. Instead, The Attendant controls a contactor, which safely handles the higher voltage and current required by 3-phase equipment.
In this configuration:
- The 3-phase motor power is routed through a properly sized contactor
- The Attendant controls the contactor coil using a standard relay
- The relay provides simple ON / OFF control of the motor while maintaining electrical isolation and safety
Required Components
Before beginning, verify the following components are available and properly rated:
- ✔ 3-pole contactor rated for:
- Motor voltage
- Motor FLA (Full Load Amps)
- ✔ Contactor coil voltage compatible with the relay supply
- Common options: 120V AC, 240V AC, or 24V AC
Important: Always verify local electrical codes and manufacturer requirements before installation.
Wiring Diagram (Example Only)
Diagram for reference only.
Not all contactors are the same. Refer to manufacturer instructions for proper wiring.
Step-by-Step Wiring Instructions
1. Power Down & Lock Out
- Turn OFF all power sources
- Lock out and tag the circuit if required
- Verify zero voltage before proceeding
2. Wire the 3-Phase Power Circuit
- Bring L1, L2, L3 from the breaker or disconnect into the LINE side of the contactor
- Connect the LOAD side of the contactor to the motor terminals
- Bond and ground the motor per code
⚠️ The Attendant never connects to L1, L2, or L3 directly.
3. Wire the Contactor Coil (Control Circuit)
- Identify the contactor coil voltage (example: 120V AC)
- Provide a dedicated, protected control power source
- Route one leg of the control power through a relay on The Attendant
When the relay closes, the contactor coil energizes and the motor starts.
Configuration in The Attendant
When programming a relay-controlled 3-phase pump in The Attendant:
- Set Brand Type to Generic
- Configure the pump as Single Speed
- Port Type is Relay and select the Relay Number the Coil is wired to.
The Attendant will provide ON / OFF control only. All motor load switching is handled by the contactor.
