Description
Overview of Low Voltage ATS Controller
- ASZ-526H Low Voltage ATS Controller is developed for automatic control of low-voltage multi-power supply. It supports standby power switching, closed-loop operation and dual/multi-power transfer, applicable to 2-incoming, 2-incoming-with-bus-coupler and 3-incoming wiring schemes.
- Low Voltage ATS Controller is applicable to power distribution systems with dual power supply for critical loads in industry, medical care, finance, data centers, government offices, post & telecommunications, coal, metallurgy, railway, marine, military facilities and expressways.
Model Description: LV Automatic Transfer Switch Relay
| Model | Control Mode | Application Mode | Remark |
|---|---|---|---|
| ASZ-526H-A20 | Dual power automatic transfer controller | Mains-Mains, Mains-Generator, Auto/Manual | |
| ASZ-526H-B20 | Dual power automatic transfer controller (with closed-loop parallel function) | Mains-Mains, Mains-Generator, Auto/Manual | |
| ASZ-526H-A21 | Dual power bus coupler automatic transfer controller | Mains-Mains-Bus Coupler, Auto/Manual | |
| ASZ-526H-B21 | Dual power bus coupler automatic transfer controller (with closed-loop parallel function) | Mains-Mains-Bus Coupler, Auto/Manual | |
| ASZ-526H-A30 | Three-power automatic transfer controller | Mains-Mains-Mains, Mains-Mains-Generator, Auto/Manual | |
| ASZ-526H-B30 | Three-power automatic transfer controller (with closed-loop parallel function) | Mains-Mains-Mains, Mains-Mains-Generator, Auto/Manual |
Features of Closed-Transition ATS Controller
- Equipped with overvoltage, undervoltage, phase loss, reverse phase sequence, overcurrent, overfrequency and underfrequency protection.
- Real-time clock display and historical data storage, circularly recording up to 500 entries.
- Compatible with 3-phase 4-wire and 3-phase 3-wire AC power systems.
- Controls closing and tripping of two incoming breakers and bus coupler breaker simultaneously to simplify control system.
- Delays closing operation till PF ready signal is received for stored-energy breakers.
- Auto/manual mode switch, manual breaker operation available under manual mode.
- Six physical switch transfer buttons on panel for convenient manual control.
- Reclosing function with enable/disable option.
- Closing output supports pulse or continuous signal mode.
- On-site programmable parameters with password protection against unauthorized operation.
- Isolated design for two neutral lines.
- LO/NO power output supplies power for breaker switching coils.
- Widely spaced AC terminals, maximum withstand voltage up to 625V AC.
- Built-in communication port adopting ModBus protocol, realizing remote control, signaling, measurement and parameter adjustment. Supports remote start/stop of generator sets and remote ATS switching.
General Technical Parameters of Low Voltage ATS Controller

Ambient Conditions
Normal Operating Atmospheric Conditions
- a. Ambient temperature: -25℃ ~ +70℃
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b. Relative humidity: 5% ~ 95%, no condensation or icing inside the device
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c. Atmospheric pressure: 80kPa ~ 106kPa
Normal Test Atmospheric Conditions
- a. Ambient temperature: +15℃ ~ +35℃
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b. Relative humidity: 45% ~ 75%
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c. Atmospheric pressure: 80kPa ~ 106kPa
Reference Test Atmospheric Conditions
- Unless specified otherwise, ambient conditions for inherent accuracy verification:
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a. Ambient temperature: (20±5)℃
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b. Relative humidity: 45% ~ 75%
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c. Atmospheric pressure: 86kPa ~ 106kPa
Storage and Transportation Conditions
- a. Transportation temperature: -40℃ ~ +70℃, relative humidity ≤85%. No irreversible changes under unpowered state.
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b. Storage temperature: -25℃ ~ +55℃, relative humidity ≤85%.
Surrounding Environment
- a. No explosion hazards, corrosive gas, conductive dust, severe mildew and violent vibration sources.
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b. Equipped with protection against rain, snow, wind, sand, dust and static electricity.
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c. Comply with Class B safety requirements of GB/T 9361-2011; grounding resistance meets Clause 5.8 of GB/T 2887-2011.
Electrical Parameters
Rated Ratings
| Item | Parameter |
|---|---|
| Operating Voltage | AC 85-480V (80%~120% fluctuation); DC 110V/220V |
| Remote Signal Voltage | DC 24V |
| AC Voltage Input | 3-phase 4-wire / 3-phase 3-wire, Max 690V AC, PT ratio adjustable |
| AC Current Input | 5A (0.05~6A), CT ratio adjustable |
| Rated Frequency | 50Hz |
Power Consumption
- AC voltage circuit: <0.5VA per phase
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AC current circuit: <0.75VA per phase
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Total power consumption: ≤15VA
Overload Capacity
- AC voltage: Continuous operation at 1.2 times rated voltage
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AC current: Continuous operation at 1.2 times rated current
Main Technical Specifications
| Item | Parameter |
|---|---|
| Remote Signaling | 12 input channels; Opto-isolated passive contact, 1500VDC isolation voltage; Internal DC24V excitation, NO/NC contact configurable; Signal resolution ≤2ms |
| Remote Control Output | 6 channels: 16A, AC250V passive output; 6 channels: 8A, AC250V passive output |
| Communication Interfaces | 1×10/100Base-TX Ethernet port; 2×RS485 interfaces |
| Reliability | MTBF ≥50000 hours |
| Insulation Performance | Insulation resistance ≥5MΩ (between circuits & ground, among separate circuits); Withstand 50Hz 2.0kV AC voltage test for 1min without breakdown/flashover; Withstand 5kV standard lightning impulse voltage between circuits & ground |
FAQ
Q: What is Make-Before-Break ATS Relay?
A: It is a switching relay that closes the standby power circuit before disconnecting the main power, realizing transient parallel connection to avoid instantaneous power outage during transfer.
Q: Definition of No-Break Automatic Transfer Switch
A: It refers to non-interruptible power transfer switch, which maintains continuous power supply to loads throughout power switching process without power cut.
Q: What does ABTD stand for?
A: ABTD is short for Automatic Bus Transfer Device, an automatic controller used for intelligent switching and interconnection of busbar power supply.
Q: Core difference between Make-Before-Break and No-Break ATS
A: Make-Before-Break adopts brief overlapping switching; No-Break ATS achieves zero power interruption for load power supply during conversion.
Q: Application scenarios of Automatic Bus Transfer Device
A: Widely used in dual or multi-busbar power distribution systems for automatic bus coupling, power switching and isolated grid power regulation.











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