RELIANCE 64418ZA field-loss electromagnetic relay
64418ZA belongs to Reliance NBR series field-loss electromagnetic relay, customized for field excitation protection of Reliance classic SCR DC drive cabinet and AutoMax control system. Original formal production has been terminated, available stock includes surplus unused original spare parts and fully tested refurbished products for old equipment maintenance replacement. It shares identical mechanical installation dimension and fixed hole layout with 64418-1X,64418RW,64418-WA,64418-YA in same product series to realize direct plug-and-place replacement without cabinet modification. This component is classified as military standard electromagnetic relay with unified NSN coding under US industrial spare part management system.
Description
Product Introduction
64418ZA belongs to Reliance NBR series field-loss electromagnetic relay, customized for field excitation protection of Reliance classic SCR DC drive cabinet and AutoMax control system. Original formal production has been terminated, available stock includes surplus unused original spare parts and fully tested refurbished products for old equipment maintenance replacement. It shares identical mechanical installation dimension and fixed hole layout with 64418-1X,64418RW,64418-WA,64418-YA in same product series to realize direct plug-and-place replacement without cabinet modification. This component is classified as military standard electromagnetic relay with unified NSN coding under US industrial spare part management system.
Model Definition
64418 is unified base part number of Reliance NBR standard relay development platform. Suffix ZA stands for exclusive customized specification variant. Letter Z corresponds to fixed coil voltage parameter grouping, letter A represents factory revised internal coil winding process and terminal wiring layout. Different suffix letters only adjust coil rated voltage and internal winding design, keeping outer dimension, contact structure and mounting dimension consistent among all 64418 family products.
Technical Specifications
Nominal rated coil voltage is 208VAC with rated coil power consumption of 7.8W. Contact configuration adopts SPDT single-pole double-throw structure, rated resistive load capacity reaches 7.5A at 250VAC, maximum permissible interrupt voltage is 300VAC. Withstand voltage between coil winding and contact assembly is 2100VAC, normal-condition insulation resistance exceeds 1000 megaohms. Mechanical switching service life exceeds 9 million operation cycles, electrical lifespan under full rated load exceeds 90000 switching times. Operating ambient temperature scope ranges from -25℃ to +65℃, storage temperature from -40℃ to +85℃, applicable relative humidity is 5%~95% under non-condensing environment, complying with UL industrial component safety certification standard.
Interface and Communication Configuration
The relay is equipped with phenolic insulating base plus integrated metal fixed support frame, four prefabricated screw fixing holes for locking installation inside drive cabinet. Front terminal adopts exposed copper screw wiring terminal for direct hard-wiring construction without detachable plug socket structure. No built-in digital bus communication port is reserved; all control signal and power circuit connection is finished via hard wiring access to DC motor field excitation loop and cabinet interlock control circuit.
Core Functions
Core application is real-time continuous monitoring of DC motor excitation loop operating current. Once field winding open circuit, field-loss or abnormal excitation failure occurs, the relay rapidly flips contact status to cut off main drive enabling interlock signal and lock drive output channel, preventing DC motor runaway overspeed and mechanical breakdown damage. Meanwhile it undertakes auxiliary logic switching for cabinet auxiliary power circuit and fault state feedback signal transmission between field on-site equipment and AutoMax master control unit.
Application Scenarios
Mainly installed inside Reliance SCR DC drive control cabinets for metallurgical rolling mill main transmission, papermaking drying cylinder driving system and chemical industry high-power DC pump drive equipment, used as core protective spare part for legacy DC drive system routine maintenance and cabinet retrofitting renovation. It also matches military standard automation control cabinet configuration per its NSN spare part attribute.
Operation and Maintenance Instructions
Cut off total input power of the whole control cabinet and wait minimum 20 minutes for complete residual charge discharge before relay disassembly or terminal wiring alteration. Implement quarterly regular maintenance: blow away accumulated dust on electromagnetic iron core by dry low-pressure compressed air, check fastening torque of terminal screws and oxidation corrosion status of copper wiring terminals. If drive equipment generates false field-loss protection alarm without actual field circuit fault, prioritize measuring coil continuity and contact surface ablation degree before whole relay replacement. Strictly avoid instantaneous overvoltage surge impacting coil terminals to prevent internal enameled wire burnout and permanent coil damage.
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