Honeywell SZR-LY2-N1 110VAC Fail-Safe DPDT Relay

Overview

Honeywell SZR-LY2-N1 110VAC Fail-Safe DPDT Relay: Fault Protection and Critical Industrial Field Reliability

The Honeywell SZR-LY2-N1 110VAC is a heavy-duty, fail-safe DPDT (Double Pole Double Throw) safety relay engineered for the most demanding industrial control environments. Designed within Honeywell’s proven SZR series platform, this relay delivers consistent switching performance under continuous production loads, high electromagnetic interference, and harsh ambient conditions including dust, moisture, high temperature, and mechanical vibration. For control engineers and maintenance teams operating in petrochemical, power generation, mining, water treatment, metallurgy, port logistics, marine, or continuous manufacturing facilities, the SZR-LY2-N1 represents a reliable, drop-in solution for critical interlock circuits and safety-rated control loops.

Operating at 110VAC coil voltage, the SZR-LY2-N1 fits directly into standard 8-pin octal relay sockets, simplifying field replacement without rewiring. Its DPDT contact configuration supports both normally open and normally closed switching paths simultaneously, enabling redundant safety logic in a single relay body. The relay’s robust construction suppresses contact bounce and arc erosion, maintaining signal integrity across thousands of switching cycles — a critical requirement in high-cycle interlock and emergency stop (E-stop) circuits.

Fail-Safe Reliability Table

Control Cabinet Protection Strategy

In a well-engineered industrial control cabinet, the SZR-LY2-N1 110VAC does not operate in isolation — it functions as part of a coordinated protection architecture. When paired with a Honeywell SZR-LY4-N1 110VAC (4PDT variant), engineers can extend switching capacity across four independent circuits within the same safety loop, maintaining full redundancy without increasing cabinet footprint. For power conditioning upstream of the relay coil, a Phoenix Contact QUINT-PS/1AC/24DC/10 DIN-rail power supply ensures stable 24VDC auxiliary voltage, preventing coil dropout caused by AC line fluctuations common in heavy industrial environments.

Surge and transient protection is equally critical. Installing a Dehn DEHNguard DG M TNC 275 surge protective device on the incoming AC feed shields the SZR-LY2-N1 coil circuit from lightning-induced transients and switching surges that can cause premature coil failure or false relay release. For communication-intensive cabinets where PROFIBUS DP or Modbus RTU signals run alongside power wiring, a Siemens 6ES7972-0BB52-0XA0 PROFIBUS connector with integrated termination resistor reduces signal reflection and bus errors that could trigger spurious relay commands.

Temperature management inside the cabinet directly affects relay longevity. A Rittal SK 3105.100 cabinet fan-and-filter unit maintains internal temperatures within the SZR-LY2-N1’s rated operating range, preventing thermal derating of contact resistance. For safety circuit monitoring, a Pilz PNOZ X3 safety relay module can be integrated in series with the SZR-LY2-N1 output contacts to provide dual-channel E-stop monitoring with cross-circuit fault detection — a requirement under IEC 62061 SIL 2 and ISO 13849-1 PLd safety standards.

Critical Industrial Safety Applications

In petrochemical and refinery environments, the SZR-LY2-N1 110VAC is deployed in emergency shutdown (ESD) panels and burner management systems (BMS) where fail-safe relay switching is mandatory. Its sealed body resists hydrocarbon vapors and corrosive atmospheres, while its fast operate and release times meet the response requirements of SIL-rated interlock loops.

In electric power generation and substation control rooms, the relay serves in protection relay auxiliary circuits, transformer tap-changer control, and generator excitation interlock panels. The 110VAC coil voltage aligns directly with standard substation auxiliary bus voltages, eliminating the need for additional voltage conversion.

In mining and mineral processing plants, the SZR-LY2-N1 controls conveyor belt interlock chains, crusher motor starters, and ventilation fan safety circuits. Its vibration resistance and wide temperature tolerance make it suitable for underground and open-pit installations where ambient conditions are extreme.

In water and wastewater treatment facilities, the relay is used in pump motor control panels, chemical dosing interlock circuits, and SCADA-connected remote I/O panels. Its long mechanical life reduces maintenance intervention frequency in unmanned pumping stations.

In metallurgy and steel production, the SZR-LY2-N1 handles high-cycle switching in rolling mill control systems, ladle crane interlocks, and furnace temperature control loops — environments where contact reliability under inductive load switching is non-negotiable.

In port and marine applications, the relay is installed in crane control panels, mooring winch interlock circuits, and shipboard auxiliary control boards, where salt-air corrosion resistance and vibration immunity are primary selection criteria.

Safety and Quality FAQ

Q1: What support terms coverage applies to the SZR-LY2-N1 110VAC?
All SZR-LY2-N1 110VAC units supplied by KNMKS carry a support terms confirmed by quotation from the date of shipment. Coverage includes coil failure, contact welding under rated load, and insulation breakdown. Support requests are supported with replacement dispatch within 5 business days upon fault confirmation.

Q2: What pre-shipment testing is performed on each unit?
Every SZR-LY2-N1 110VAC undergoes 100% individual testing prior to dispatch: coil pull-in voltage verification at 110VAC, contact continuity check across all NO and NC paths, and insulation resistance measurement at 500VDC. Test records are available upon request for quality-critical procurement.

Q3: Is the SZR-LY2-N1 compatible with standard 8-pin octal relay sockets?
Yes. The SZR-LY2-N1 is fully compatible with standard 8-pin octal sockets including the Honeywell PTF08A, Omron PYF08A, and equivalent DIN-rail or panel-mount socket bases. No wiring modification is required for direct field replacement of existing LY2 or SZR-series relays.

Q4: Can KNMKS support long-term or repeat supply of the SZR-LY2-N1?
Yes. KNMKS maintains forward buffer stock of the SZR-LY2-N1 110VAC to support planned maintenance schedules, annual spare part procurement programs, and emergency replacement orders. Long-term supply agreements with fixed pricing are available for facilities requiring guaranteed availability over 12–36 month horizons.

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Product Identification

Brand / Ecosystem

Honeywell
Honeywell

Model / Series

SZR-LY2-N1 110VAC

Product Family

Relays & Interface

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Available on request after model and quantity confirmation

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B2B RFQ, replacement inquiry and project spare-part request

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Exact SKU, brand, series, quantity, nameplate photos and destination country are checked before quotation

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Interface range

Relays, isolation and signal modules

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Coil voltage and contact rating

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Panel wiring and signal protection

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• Relay base and module matching
• Signal isolation and protection options
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