Y-703 Automatic Transfer Switch Controller - China Suppliers & Factory with CE Certification

LMS1-LA as our ingenuity research and development of a new generation of dual power automatic transfer switch, in the performance and technology to achieve a major breakthrough. The product provides 63A, 125A, 250A, 400A, 630A and other rated current specifications, whether it is the continuous operation of massive servers in data centers, or the uninterrupted power supply of life support equipment in hospital ICU wards, the stable operation of elevator and fire fighting system in high-rise buildings can fully meet the power demand in different scenarios. ​

The Y-703 controller is a split type dual power transfer switch controller. It detects the abnormality of grid parameters (over-voltage, under-voltage, phase failure, over-frequency, under-frequency, phase sequence, etc.), and then automatically controls the transfer switch (TSE) to convert to the appropriate power supply according to the predetermined operation mode, ensuring the continuity of power supply on the load side.

Functional Characteristics

• The measurement and control system is constructed with the microcontroller as the core, and the basic parameters of the power grid are calculated by the true RMS.
• The conversion delay and operation mode can be adjusted to meet different application scenarios.
• The combination of segment code LCD and LED LAMP provides clear and accurate information.
• Configuration of programmable relay output contacts, active and passive fire signal interface, optional communication interface.
• Able to check the switching times and fault records.

Main Technical Parameters

Working power supply	One-line/two-line A-phase power supply, voltage range AC80~320V, 50/60Hz
Operation mode of TSE	Self-input and self-recover (I circuit priority or II circuit priority can be selected) — Note 1, and mutual standby (self-input without self-recover) — Note 2
Real-time display of power grid parameters	Display the voltage and frequency of I circuit and II circuit cyclically
Voltage measurement method	3 phase 4 line, neutral voltage measurement
Range and accuracy of voltage measurement	60~350V, accuracy ±1% + 1 display word
Frequency measurement range	40Hz~75Hz
Voltage detection function	Lost phase detection, three-phase voltage over and under voltage detection
Phase sequence detection function	The default value is off. The buzzer alarms when the function is turned on
Frequency detection function	By default, transfer is not cast. If you need to transfer, you can enable it in the Setting
Passive fire input	Connect passive switch or contact outside
Active fire input	Connect DC9-36V active signal outside
Transfer time delay (adjustable)	0~240s
Overvoltage and under-voltage (adjustable)	Under-voltage: 100 to 200V; Overvoltage: 200 to 300V
Start generator function	Relay contact output (programmable relay)
Generator start and stop time	0–240s
Programmable relay	Passive contact output, 3A/250V resistance, start generator is defaulted
Communication function (optional)	RS485 isolation interface over MODBUS
Recording function	It can record the failure transfer times, the voltage of each phase when they are failed and other parameters

Note 1: Self-input and Self-recover (I line priority): When normal power is failed (lost phase, overvoltage, under-voltage), TSE will transfer to standby power automatically. When the main power is restored, it will transfer back to normal power.

Note 2: Self-input without self-recover (two-line priority): When the normal power is failed (lost phase, over-voltage, under-voltage), the TSE will transfer to standby power automatically. When the main power is restored, it will not transfer back to normal power — only when the standby power is failed, it will transfer back to normal power.

Note 3: ATS transfer failure status indicator: If the switch cannot complete the transfer within the specified time, the controller will stop transfer and make indicator light 8 flash simultaneously. Press the "Automatic/Manual" button to cancel the transfer failure and change the indicator; indicator 8 returns to normal state.

Controller Function

Serial	Name	Instruction
①	Main power status indicator	L1-N, L2-N, and L3-N indicate whether the A/B/C phase voltage of main power is normal. If the voltage is normal, it is on; if it is abnormal, it is off.
②	Main power closing indicator	When the main power closing signal is detected, the light will be on, and then transfer to main power delay — the light flashing.
③	LCD display	Display measurement value and set parameters and other information.
④	Standby power closing indicator	When the standby power closing signal is detected, the light will be on, and then transfer to standby power delay — the light flashing.
⑤	Standby power status indicator	L1-N, L2-N, and L3-N indicate whether the A/B/C phase voltage of standby power is normal. If the voltage is normal, it is on; if it is abnormal, it is off.

Icon	Function	Instruction
	Manual / Auto	Press this button to transfer between manual and automatic working mode (only valid in the main interface; invalid in parameter setting state).
	Double Off / Return	In manual mode it is double off. In parameter setting state, it is return. Press this button to exit parameter setting.
	Main power closing / Data plus	In manual mode, it is the main power closing key. In the menu browsing interface, it is the menu flip key. In the parameter setting state, it is the data plus key.
	Standby power closing / Data minus	In manual mode, it is the standby power closing key. In the menu browsing interface, it is the menu down scroll key. In the parameter setting state, it is the data minus key.
	Set / Confirm	Press this key on the home screen to enter the menu browsing screen. Press this key on the menu browsing screen to set or confirm parameters.

Overall Dimensions

Frequently Asked Questions (FAQ)

QWhat is the Y-703 controller used for?

The Y-703 is a split-type dual power transfer switch controller. It monitors grid parameters such as over-voltage, under-voltage, phase failure, and frequency abnormalities, then automatically controls the transfer switch (TSE) to switch to the appropriate power supply, ensuring uninterrupted power on the load side.

QWhat operation modes does the Y-703 support?

The Y-703 supports two main operation modes: (1) Self-input and self-recover — the controller automatically transfers to standby power when the main power fails and returns to main power once it is restored; and (2) Mutual standby (self-input without self-recover) — the controller transfers to standby power when the main power fails, but will not transfer back until the standby power also fails.

QWhat voltage and frequency ranges does the Y-703 support?

The Y-703 working power supply accepts AC80~320V at 50/60Hz. Its voltage measurement range is 60~350V with an accuracy of ±1% + 1 display word, and the frequency measurement range is 40Hz~75Hz.

QDoes the Y-703 support communication interfaces?

Yes, the Y-703 optionally supports an RS485 isolation communication interface using the MODBUS protocol, allowing it to be integrated into building management or industrial monitoring systems.

QHow does the Y-703 handle a transfer failure?

If the transfer switch cannot complete the transfer within the specified time, the controller will stop the transfer attempt and indicator light 8 will begin flashing to signal the failure. The user can press the "Automatic/Manual" button to cancel the transfer failure state and return indicator 8 to normal.

QCan the Y-703 record fault history and switching events?

Yes, the Y-703 features a built-in recording function that logs failure transfer times, the voltage of each phase at the time of the fault, and other relevant parameters. This helps with maintenance diagnostics and system auditing.