VIOX FCT18-ST Start-Delta Timer Relay

Overview

The VIOX FCT18-ST is a specialized start-delta timer relay designed primarily for controlling the starting sequence of three-phase motors. This DIN rail-mounted device provides precise timing control for the star-delta (also known as wye-delta) starting method, which is widely used to reduce inrush current and provide smoother motor acceleration in industrial applications.

Key Features and Benefits

• Specialized Design: Specifically engineered for controlling the delay ON time of motors in star/delta configuration
• Versatile Time Ranges: Adjustable from as quick as 0.1 seconds to as long as 40 minutes
• Wide Power Supply Compatibility: Operates across 12 to 240 VAC/DC power systems
• User-Friendly Setup: Easy configuration with wiring diagrams conveniently located on the side of the product
• Exceptional Precision: Time error less than 0.5% for reliable operation
• Robust Performance: Strong anti-interference capability to ensure stable functioning in noisy electrical environments

Technical Specifications

Model Identification

The model numbering system FCT18-ST 2 W breaks down as follows:

Position	Code	Meaning
1. Function	ST	Star-delta relay
2. Type of output	2	2CO contacts
3. Supply voltage	W	AC/DC12-240V

Other supply voltage options include:

• A: AC230V
• D: DC24V

Input and Power Specifications

Parameter	Specification
Input Terminal	A1-A2
Voltage range	AC 230V / DC24V / AC/DC 12-240V
Power consumption	AC 3.5VA / DC 2.0W
Voltage tolerance	-15% ~ +10%
Supply indication	Green LED
Relay indication	Red LED

Timing Specifications

Parameter	Specification
Time ranges	0.1s-40min
Time setting	Via rotary button
Time deviation	0.1%
Repeat accuracy	0.5%
Temperature coefficient	0.05%/°C, at=20°C (0.05%/°F, ≈68°F)

Output Specifications

Parameter	Specification
Output contact	2×SPDT (Single Pole Double Throw)
Rated current	2×16A
Mechanical life	1×107
Electrical life	1×105

Environmental and Physical Specifications

Parameter	Specification
Operating temperature	-20 … +60 °C / -40 … +85 °C
Mounting	DIN rail EN/IEC 60715
IP Rating	IP20
Stripping length	7mm (0.28in)
Installed altitude	≤2200m
Pollution level	2
Max cable size	AWG13-20 0.4N·m
Dimension	90mm×18mm×64mm
Weight	about 90g
Standards	GB/T 14048.5, IEC60947-5-1, EN6812-1

How the FCT18-ST Timer Relay Works

Timing Function

The FCT18-ST provides precise timing control for star-delta motor starting with the following sequence:

1. When power (Un) is applied to the relay, the timing sequence begins
2. The first relay (R1, terminals 11-14) activates immediately, placing the motor in star configuration
3. After the preset time T1 elapses, R1 deactivates, creating a brief pause in the motor circuit
4. Following this brief pause, the second relay (R2, terminals 21-24) activates, switching the motor to delta configuration for continued operation

Time Setting Options

The FCT18-ST offers 10 different time range settings to accommodate various motor sizes and application requirements:

• 0.1-1s: For very small motors or testing purposes
• 1-10s: Common setting for small to medium motors
• 0.1-1m: For medium-sized motors
• 1-10m: For larger motors requiring gradual acceleration
• 1.5-15m: For specialized applications with extended ramp-up requirements
• 2-20m: For very large motors or high-inertia loads
• 2.5-25m: For heavy-duty industrial applications
• 3-30m: For extreme heavy-duty applications
• 3.5-35m: For specialized industrial processes
• 4-40m: Maximum range for the most demanding applications

Ratio Setting Feature

One of the unique advantages of the FCT18-ST is its adjustable ratio setting, which allows fine-tuning of the timing function. The ratio setting can be adjusted from 10% to 100% in 5% increments, providing precise control over the star-to-delta transition timing. This feature enables optimal motor starting performance across various load conditions.

Applications of FCT18-ST Start-Delta Timer Relay

Industrial Motor Control

The primary application of the FCT18-ST is controlling three-phase motors using the star-delta starting method. This technique is widely used in industrial settings to reduce starting current and provide smoother acceleration for motors typically ranging from 5HP (3.7kW) to 100HP (75kW) and beyond. Common applications include:

• Conveyor systems
• Pumping stations
• HVAC equipment
• Compressors
• Industrial fans and blowers
• Material handling equipment
• Machine tools
• Production line machinery

Benefits of Star-Delta Starting with FCT18-ST

Using the FCT18-ST timer relay for star-delta starting offers numerous advantages:

• Reduced Starting Current: Typically limits inrush current to about 33% of direct-on-line starting
• Minimized Voltage Dips: Prevents power quality issues during motor startup
• Extended Motor Life: Reduced mechanical and thermal stress during starting
• Lower Energy Costs: Efficient starting sequence reduces peak demand charges
• Compliance with Utility Requirements: Meets regulations limiting starting current
• Smoother Acceleration: Gradual application of torque protects connected machinery

Installation and Wiring

Mounting Instructions

The FCT18-ST is designed for easy installation on standard 35mm DIN rails according to EN/IEC 60715. The compact dimensions (90mm×18mm×64mm) make it ideal for installation in control panels with limited space. With an IP20 protection rating, the relay should be installed in appropriate enclosures to protect against dust and moisture.

Wiring Diagram

The FCT18-ST features a straightforward wiring configuration:

• A1: DC+ / AC L (Line)
• A2: DC- / AC N (Neutral)
• Terminals 11-14: First relay output (Star configuration)
• Terminals 21-24: Second relay output (Delta configuration)

For proper operation, connect the power supply to terminals A1-A2, and connect the star and delta contactors to the respective relay outputs. Detailed wiring diagrams are provided on the side of the product for easy reference during installation.

Dimension

Configuration and Operation

Time Range Selection

To set up the FCT18-ST for your specific application:

1. Select the appropriate time range using the top rotary dial
2. Fine-tune the timing within the selected range using the second rotary dial
3. Set the desired ratio using the bottom rotary dial

Operational Indicators

The FCT18-ST includes two LED indicators to provide at-a-glance status information:

• Green LED: Illuminates when power is supplied to the relay
• Red LED: Illuminates when the relay is activated

Troubleshooting and Maintenance

Common Issues and Solutions

Issue	Possible Cause	Solution
No LEDs illuminate	No power to the relay	Check power supply connections at A1-A2
Timer does not activate outputs	Incorrect time settings	Verify time range and ratio settings
Erratic operation	Electrical interference	Improve wiring separation, add suppression devices
Motor fails to start in delta	Incorrect transition timing	Adjust time settings for appropriate motor size

Maintenance Requirements

The FCT18-ST is designed for long-term reliability with minimal maintenance. With a mechanical life of 10 million operations and an electrical life of 100,000 operations, the relay provides dependable service in demanding industrial environments. Periodic inspection of terminal connections is recommended to ensure secure wiring.

Advantages of VIOX FCT18-ST Over Competitors

Superior Technical Features

• Exceptional Timing Accuracy: With a time error less than 0.5% and a temperature coefficient of just 0.05%/°C, the FCT18-ST provides more precise control than standard timer relays
• Wide Voltage Range: The flexible 12-240 VAC/DC power supply compatibility eliminates the need for multiple relay models in varied installations
• Enhanced EMC Performance: Strong anti-interference capability ensures reliable operation even in electrically noisy industrial environments

Practical Design Advantages

• Intuitive Configuration: Clear markings and accessible controls simplify setup and adjustment
• Compact Size: The space-saving 18mm width design (just one module wide) conserves valuable DIN rail space
• On-Device Documentation: Integrated wiring diagrams eliminate the need for separate installation instructions

Industries and Applications

Key Industry Applications

• Manufacturing: Production machinery, assembly lines, material handling systems
• Water/Wastewater: Pump control for treatment facilities and distribution systems
• HVAC: Air handling units, cooling towers, and large ventilation systems
• Mining: Conveyor systems, crushers, and processing equipment
• Oil & Gas: Pump stations, compressors, and processing equipment
• Food & Beverage: Processing equipment, mixing systems, and packaging machinery

Application Examples

Example 1: Industrial Water Pump

For a 30HP water pump in a municipal water system, the FCT18-ST can be configured with a 5-second timing to provide a smooth transition from star to delta starting. This reduces water hammer effects in the piping system while limiting starting current to protect the electrical infrastructure.

Example 2: Conveyor System

In a mining operation with heavy-duty conveyors, the FCT18-ST can be set with a longer transition time of 10-15 seconds to gradually accelerate the loaded belt, preventing material spillage and reducing mechanical stress on the drive components.

Compliance and Certification

The FCT18-ST complies with international standards including:

• GB/T 14048.5
• IEC60947-5-1
• EN6812-1

These certifications ensure the relay meets stringent requirements for industrial control equipment in terms of performance, safety, and electromagnetic compatibility.

Conclusion

The VIOX FCT18-ST Start-Delta Timer Relay represents a high-quality, versatile solution for motor starting applications across numerous industries. With its precise timing control, robust construction, and user-friendly design, this relay provides reliable performance in demanding industrial environments while extending motor life and reducing electrical stress during startup.

For additional information or to discuss your specific application requirements, please contact our technical support team or request a detailed product datasheet.