Why Choose the ABB SQZ3 Phase & Sequence Relay?
The ABB SQZ3 is a compact phase and sequence monitoring relay designed for continuous supervision of three-phase electrical networks. Operating on 400 V AC systems, it monitors phase sequence, phase failure and minimum voltage to help protect motors, machinery and other three-phase equipment against potentially damaging supply conditions.
The SQZ3 continuously checks the three-phase supply and operates its safety switching output contact when a monitored fault is detected. Minimum-voltage monitoring is adjustable from 70–100% of the nominal voltage, while the intervention delay for minimum-voltage faults can be set between 2 and 20 s, allowing the monitoring response to be adapted to the application.
With a 1 changeover (1CO) output contact rated at 10 A, 250 V AC at cosφ = 1, the SQZ3 can interface with acoustic alarms, motor-control contactors and circuit-breakers equipped with operating coils. Its three-module format and IP20 protection make it suitable for installation in electrical distribution boards and industrial control panels.
Key Advantages
- Continuous three-phase network monitoring for improved equipment protection.
- Monitors phase sequence, phase failure and minimum voltage.
- Designed specifically for 400 V AC three-phase networks.
- Adjustable minimum-voltage threshold from 70–100% of Vn.
- Adjustable 2–20 s intervention delay for minimum-voltage monitoring.
- 1CO safety switching output for connection to alarms and control equipment.
- Compact three-module format for straightforward panel integration.
Key Features
- ABB SQZ3 phase and sequence relay.
- 400 V AC nominal supply voltage.
- 50/60 Hz operating frequency.
- Continuous phase-sequence monitoring.
- Continuous phase-failure monitoring.
- Adjustable minimum-voltage monitoring.
- 70–100% of Vn minimum-voltage adjustment range.
- 2–20 s adjustable delay for minimum-voltage intervention.
- 1CO, 250 V AC, 10 A safety switching contact at cosφ = 1.
- LED indication for monitoring status.
- IP20 protection rating.
- Compact three-module construction.
Reliable Monitoring for Three-Phase Electrical Networks
Incorrect phase sequence, loss of a phase or excessive voltage reduction can cause three-phase motors and connected machinery to operate incorrectly or stop unexpectedly. The ABB SQZ3 continuously supervises these supply conditions and changes the state of its output relay when a monitored fault occurs, allowing appropriate control or protective action to be initiated.
The safety switching contact can be incorporated into control circuits for acoustic alarms, motor-control contactors or circuit-breakers fitted with coils. Adjustable minimum-voltage sensitivity and intervention delay provide flexibility for applications where brief voltage variations need to be distinguished from sustained undervoltage conditions.
Typical Applications
- Three-phase motor protection and monitoring.
- Industrial machinery and production equipment.
- Motor-control centres and electrical control panels.
- Pumps, fans and compressor installations.
- Conveyors and material-handling systems.
- Phase-failure and phase-sequence supervision.
- Undervoltage monitoring of 400 V AC three-phase supplies.
- Alarm, contactor and circuit-breaker control circuits.
