Motor Control Accessories: What to Identify Before Ordering

Updated: August 6, 2026

TL;DR

Motor control components must be matched to the motor, equipment, control system, environment, and approved design. Before ordering, gather the complete motor and equipment nameplate information, existing manufacturer part numbers, controller type, control voltage, connection details, enclosure requirements, dimensions, approvals, and system documentation. A similar-looking component or a device with a higher electrical rating is not automatically a suitable replacement.

What are motor control accessories?

Motor control systems may include several product families that work together to start, stop, control, monitor, isolate, or protect a motor and its related equipment.

Depending on the approved system design, the bill of material may include:

• Contactors and motor starters
• Overload relays and motor-protection devices
• Variable-frequency drives and soft starters
• Control relays, timers, and monitoring devices
• Control stations, pushbuttons, selector switches, and pilot lights
• Control transformers and power supplies
• Enclosures, mounting components, replacement parts, and accessories

These products are not interchangeable simply because they appear together in a motor-control system. Each component must be evaluated against the equipment documentation and the requirements established by the responsible designer, manufacturer, panel shop, facility, or other qualified professional.

Start by defining the request

Tell the supplier which situation applies:

• Replacing an existing component with the same part
• Replacing a discontinued component
• Repairing original equipment
• Ordering parts from an approved drawing or specification
• Modifying an existing machine or control panel
• Building a new motor-control system

A verified direct replacement may be identified through the complete manufacturer part number and official replacement documentation. Modifications, substitutions, and new applications require review by the professional responsible for the system.

Motor and equipment information to collect

Provide the information shown on the motor, driven equipment, machine, and existing control equipment:

• Motor manufacturer and complete model number
• Horsepower or kilowatt rating
• Rated voltage and phase
• Nameplate current
• Frequency
• Service factor, duty, and temperature information when shown
• Machine or equipment manufacturer and model
• Existing controller or panel identification
• Approved drawings, schedules, or equipment manuals

Copy the information exactly. Do not estimate unreadable nameplate values or assume that two motors with the same horsepower use identical control equipment.

Record every part number and suffix

For an existing component, document:

• Manufacturer
• Complete catalog or model number
• Product series
• Every letter, number, suffix, and option code
• Coil or control voltage
• Contact or pole configuration
• Trip, control, or accessory module identification
• Previous or superseded part number
• Date code or revision when relevant

A suffix may identify a different coil, contact arrangement, communication option, trip range, enclosure, mounting style, connector, or certification. A shortened part number is not enough to confirm a replacement.

Identify the controller and control system

Provide the documented controller and control-system details, including:

• Existing starter, contactor, soft starter, or drive type
• Forward, reversing, multispeed, or other approved configuration
• Control voltage and frequency
• Number and type of auxiliary contacts
• Required operator devices and indicators
• PLC, network, communication, or monitoring requirements
• Required reset, test, selector, or interlocking functions
• Existing wiring diagram or approved control schematic

Do not determine the control sequence by operating, bypassing, rewiring, or testing machinery solely for product identification.

Confirm the physical configuration

Similar electrical specifications do not guarantee that a component will fit the existing equipment. Record:

• Open, enclosed, panel-mounted, DIN-rail, or other mounting style
• Overall width, height, and depth
• Mounting-hole or rail arrangement
• Terminal location and orientation
• Wire-entry or connector location
• Available space around the component
• Required accessories, mounting kits, covers, or adapters

Use the manufacturer’s dimensional drawing whenever possible. Photographs can help identify a component, but they do not replace verified dimensions or part data.

Document the operating environment

Describe the actual conditions around the equipment:

• Indoor or outdoor location
• Ambient-temperature range
• Water, moisture, condensation, or washdown exposure
• Dust, fibers, debris, oil, or coolant
• Corrosive chemicals or salt exposure
• Vibration, shock, or unusual movement
• Hazardous or classified-location requirements
• Food, pharmaceutical, or sanitary requirements
• Existing enclosure type and material

General descriptions such as outdoor, industrial, rooftop, coastal, or washdown do not establish the required enclosure or component rating. Use the exact environmental requirements from the approved plans, equipment documentation, or responsible designer.

Confirm system ratings and approvals

Motor-control components may be part of a coordinated assembly. Provide any available documentation showing:

• Panel or equipment nameplate information
• Required short-circuit rating or approved component combination
• Disconnecting and protection equipment specified for the system
• Required listings, certifications, or manufacturer approvals
• Facility or project standards
• Machine-safety or risk-assessment requirements
• Authority Having Jurisdiction requirements when documented

Do not assume that selecting an individually listed component preserves the approval or rating of an assembled panel or machine. Substitutions should be reviewed against the documentation for the complete system.

When should the request be escalated?

Have the selection reviewed by the equipment manufacturer, controls engineer, approved panel shop, machine-safety professional, project engineer, or other responsible qualified person when:

• The original part number is missing or unreadable
• The component has been discontinued
• No manufacturer-approved replacement can be confirmed
• The motor, machine, controller, or control sequence has changed
• The replacement requires changes to wiring, programming, mounting, protection, or enclosure construction
• The component participates in an emergency, guarding, interlock, or other safety-related function
• The equipment is in a hazardous or classified location
• System ratings, approvals, or required documentation cannot be confirmed

What should you bring to Revco?

Before requesting a quote or replacement, gather as much of the following as possible:

• Motor and machine nameplate information
• Complete existing component part numbers
• Panel, starter, controller, or drive identification
• Control voltage and required contact configuration
• Approved drawings, schedules, manuals, and replacement-parts lists
• Dimensional drawings or verified measurements
• Environmental and enclosure requirements
• Required listings and approvals
• Clear photographs of safely accessible labels and components
• Quantity and required date

Revco can use this information to search available product data and manufacturer documentation. Final component selection, system coordination, settings, installation, commissioning, and approval remain with the qualified professionals responsible for the equipment.

Browse Revco’s industrial control products, motor control accessories, motor starters, or drives and accessories. Contact your preferred branch before visiting to discuss the application information and current availability.

About Revco Lighting & Electrical Supply

Revco Lighting & Electrical Supply operates six locations across Suffolk County, New York. Visit the Revco locations page to find the branch most convenient for your project.

Safety and design notice

This article is a product-identification and quote-preparation guide. It is not a motor-control design, component-sizing, protection, wiring, programming, installation, commissioning, maintenance, testing, or troubleshooting guide. Follow approved plans, equipment-manufacturer documentation, applicable requirements, and the direction of qualified professionals responsible for the system. Servicing and maintenance must follow the employer’s established hazardous-energy-control program. See OSHA’s Control of Hazardous Energy information.