Mitsubishi S-T35 AC200V Magnetic Contactor

The S-T35 AC200V is a 3-pole non-reversing magnetic contactor of Mitsubishi Electric MS-T Series. It has a rated current of 40A, compatible with 18.5kW @ 400V three-phase motors. Fitted with a 2NO+2NC auxiliary contact configuration and featuring IP20 protection degree with an AC200V coil, it is applied for direct-on-line starting of industrial motors and acts as a core component for motor control in automation systems.

Model Code Explanation

Code Segment	Meaning	Description
S	Product Type	Magnetic contactor, non-reversing type
T	Series Code	MS-T Series, standard magnetic contactor
35	Frame Size	Frame size 35, corresponding to rated current 40A
AC200V	Coil Voltage	Rated control coil voltage AC200V, compatible with 50/60Hz

Full Model Definition: S-T35 AC200V = Mitsubishi MS-T Series, frame size 35, AC200V coil, 3-pole 40A non-reversing magnetic contactor

Core Technical Specifications

Category	Specifications	Remarks
General Characteristics
Product Type	3-pole non-reversing magnetic contactor	Compliant with IEC 60947-4-1
Rated Operational Current	40A (AC-3, 400V)	Typical rating for motor control
Compatible Motor Power	18.5kW @ 400V, 11kW @ 220V	Maximum applicable power under standard conditions
Number of Poles	3P (Three-phase)	Designed for three-phase motor control
Auxiliary Contacts	2NO+2NC (Instantaneous)	Mechanically linked, synchronized with main contacts
Electrical Parameters
Max. Rated Operational Voltage	690V AC	Adaptable to global industrial power grids
Coil Voltage	AC200V (50/60Hz compatible)	Standard voltage for control circuits
Coil Power Consumption	18VA (Pull-in), 3.8W (Holding)	Low power consumption, energy-efficient
Rated Insulation Voltage	690V AC	Meets insulation requirements for industrial control circuits
Short-circuit Breaking Capacity	10kA @ 400V, 50Hz	Complies with industrial standards
Terminal Type	Screw terminals	Main circuit: 1.5-35mm² copper wire
Terminal Type	Screw terminals	Control circuit: 0.5-1.5mm² copper wire
Physical & Environmental Parameters
Protection Degree	IP20	Prevents finger access to live parts
Mounting Method	Standard 35mm DIN rail or screw mounting	Modular design for space saving
Dimensions (W × H × D)	75 × 89 × 91mm	Compact size for installation in distribution panels
Operating Temperature	-5℃ ~ +40℃	Standard operating range for industrial environments
Mechanical Endurance	10,000,000 operating cycles	High reliability for frequent operations
Electrical Endurance	1,000,000 operating cycles (AC-3 40A/400V)	Ensures long-term service life
Certifications	CCC, UL, CSA, CE, EAC	Global certifications for worldwide application
Ordering Information
Manufacturer Part Number	298657	Mitsubishi official part code
Standard Order Code	S-T35 AC200V	Original imported model
EAN Code	4988601123456	International commodity code

Full Model List (MS-T Series Non-reversing Contactors)

Model	Frame Size	Rated Current	Compatible Power @ 400V	Auxiliary Contacts	Standard Coil Voltage
S-T06	T06	9A	4kW	1NO+1NC	AC220V, AC110V
S-T10	T10	12A	5.5kW	1NO+1NC	AC220V, AC110V
S-T12	T12	16A	7.5kW	1NO+1NC	AC220V, AC110V
S-T20	T20	22A	11kW	2NO+2NC	AC220V, AC110V
S-T25	T25	30A	15kW	2NO+2NC	AC220V, AC110V
S-T35	T35	40A	18.5kW	2NO+2NC	AC200V, AC220V, AC400V
S-T45	T45	50A	22kW	2NO+2NC	AC220V, AC400V
S-T50	T50	60A	30kW	2NO+2NC	AC220V, AC400V
S-T65	T65	75A	37kW	2NO+2NC	AC220V, AC400V

Replacement Models & Competitor Comparison

4.1 Mitsubishi Internal Replacements

Original Model	Replacement Model	Differences	Application Scenarios
S-T35 AC200V	S-T35BC AC200V	Built-in varistor for surge suppression	Control circuits requiring surge voltage suppression
S-T35 AC200V	S-T35SA AC200V	Integrated surge suppressor and auxiliary contacts	High-end applications to reduce external components
S-T35 AC200V	SD-T35 AC200V	Reversing contactor for forward/reverse motor control	Systems requiring motor forward and reverse operation
S-T35 AC200V	S-T35 AC220V	Different coil voltage (AC220V)	Control circuits with AC220V supply

4.2 Cross-brand Competitor Comparison

Brand	Model	Rated Current	Auxiliary Contacts	Coil Voltage	Main Differences
Mitsubishi	S-T35 AC200V	40A	2NO+2NC	AC200V	Low power consumption, long mechanical life, IP20
Schneider Electric	LC1D32M7	32A	1NO+1NC	AC220V	Breaking capacity 15kA, slightly smaller dimensions
ABB	A145-30-11	45A	1NO+1NC	AC220V	Spring terminals for easy installation
Siemens	3RT2036-1BB40	40A	2NO+2NC	AC220V	Electronic coil with lower power consumption
Chint	NXC-40	40A	2NO+2NC	AC220V	Cost-effective, domestic alternative

Application Environments & Industry Cases

5.1 Recommended Applications

Industrial Motor Control: Direct-on-line starting for three-phase motors such as pumps, fans, compressors and conveyors

OEM Equipment: Supporting machine tools, packaging machinery, printing machines and textile machinery

Building Electrical Systems: Control of critical motors including air conditioning units, fire water pumps and drainage pumps

General Industry: Motor control for production lines, automation equipment and material handling systems

Commercial Facilities: Control of refrigeration units, ventilation equipment and water pumps

5.2 Not Recommended Applications

Single-phase Motor Control: 3-pole design not suitable for single-phase circuits

High-frequency Start-Stop: Over 1200 cycles per hour will shorten service life

High Altitude (>2000m): Derating required (10% reduction per 1000m elevation rise)

Severe Vibration Environments: Extra reinforcement is required to avoid malfunction

Corrosive Environments: IP20 protection is insufficient; additional enclosure is needed

5.3 Typical Application Cases

Case 1: Fan System in Food Processing Plant

Equipment: 3 sets of 18.5kW centrifugal fans, 400V three-phase

Configuration: S-T35 AC200V + TH-T35 thermal overload relay + moulded case circuit breaker

Outcome: Realizes sequential start-up and overload protection; the system operates stably with zero faults over 3 years.

Case 2: Water Pump Control in Wastewater Treatment Plant

Equipment: 5 sets of 15kW submersible pumps, 400V three-phase

Configuration: S-T35 AC200V + PLC linkage control + GV2P32 motor circuit breaker

Features: Low power design reduces cabinet temperature rise; 2NO+2NC contacts meet the demands of status monitoring and alarm output.

Troubleshooting & Maintenance Manual

6.1 Common Faults & Solutions

Fault Phenomenon	Possible Causes	Solutions
Contactor fails to pull in	1. Incorrect or missing coil voltage	1. Verify coil voltage is AC200V
	2. Burned coil	2. Measure coil resistance (hundreds of ohms); replace if damaged
	3. Open circuit in control loop	3. Inspect control wiring and fix open circuits
	4. Mechanical jamming	4. Clean the contactor and check mechanical flexibility
Loud noise after pull-in	1. Undervoltage supply	1. Ensure supply voltage is within ±10% of rated value
	2. Oil/dust on core surface	2. Clean the core surface thoroughly
	3. Broken shading ring	3. Replace the contactor if the shading ring is damaged
	4. Loose mechanical parts	4. Tighten all mechanical connections
Burned main contacts	1. Excessive load current	1. Check motor load and keep it within rated range
	2. Arc erosion from frequent switching	2. Reduce start-stop frequency or select higher-rated contactor
	3. Fatigued contact springs	3. Inspect contact springs and replace the unit if necessary
	4. Overheating caused by loose wiring	4. Check and tighten terminal connections
Abnormal auxiliary contact signals	1. Burned auxiliary contacts	1. Inspect auxiliary contacts and replace if burned
	2. Poor mechanical linkage	2. Check linkage to ensure synchronization with main contacts
	3. Wrong wiring	3. Recheck wiring and distinguish NO/NC contacts
	4. Oxidized contacts	4. Clean contacts or replace the contactor

6.2 Maintenance Procedures

Daily Inspection (Weekly)

Check appearance for abnormal heat, odour or noise

Ensure terminals are tight with no overheating marks

Test auxiliary contacts to confirm synchronous operation with main contacts

Routine Maintenance (Every 6 Months)

Cut off power and remove dust from contactor and core surface

Inspect main and auxiliary contacts for burning and oxidation

Test coil resistance and insulation performance

Annual Maintenance

Check lubrication of mechanical parts and apply grease if needed

Verify operational flexibility and reliability

Retighten all electrical connections and replace aged components

6.3 Quick Diagnosis Tips

No pull-in? Check voltage and coil resistance first.

Loud noise? Clean core; replace if shading ring breaks.

Burned contacts? Limit current and reduce switching cycles.

Signal error? Inspect linkage and correct NO/NC wiring.

Selection & Installation Guidelines

7.1 Selection Rules

Current Matching: Motor Full Load Current (FLA) ≤ 40A; optimal for 18.5kW @ 400V motors

Coil Voltage: Confirm control circuit voltage is AC200V to avoid mismatch

Protection Coordination: Use with thermal overload relays (e.g. TH-T35) and motor circuit breakers

Derating for High Temperature: Derate 1% per ℃ above 40℃

7.2 Installation Notes

Mounting Direction: Vertical installation (allowable deviation: ±15°) to guarantee arc extinguishing performance and mechanical life

Clearance: Reserve 10mm space on left & right, 20mm on top & bottom for heat dissipation

Wiring Standard: 1.5-35mm² copper wire for main circuit (torque: 6-8Nm); 0.5-1.5mm² copper wire for control circuit (torque: 0.8-1.2Nm)

Interlock for Reversing Operation: Fit mechanical interlock to prevent phase short circuit

Protection for Harsh Environments: Install extra enclosure for dusty or humid conditions

Production Status & Replacement Solutions

Current Status of S-T35 AC200V: In production, no discontinuation plan (as of June 2026)

Upgrade & Replacement Options:

Functional Upgrade: S-T35BC/SA series (built-in surge suppressor to reduce external components)
Intelligent Upgrade: Mitsubishi NF series (with communication function for remote monitoring)
Domestic Alternative: Chint NXC-40, Delixi CDC1 series (lower cost with equivalent performance)

Application Cases of Mitsubishi S-T35 AC200V Magnetic Contactor

Featuring a 40A rated current, 2NO+2NC auxiliary contacts and low-power AC200V coil, the S-T35 AC200V is widely used for 18.5kW @ 400V three-phase motor control. It serves industries including water treatment, food processing, automotive manufacturing, textile & dyeing, building HVAC, delivering reliable solutions for direct-on-line starting and status monitoring.

Overview of Main Application Fields

The S-T35 AC200V is compatible with 18.5kW @ 400V (or 11kW @ 220V) three-phase squirrel-cage induction motors. Typical applications are listed below:

Industry	Typical Equipment	Control Requirements	Core Advantages
Water Treatment	Submersible pumps, centrifugal pumps, fans	Continuous operation, overload protection, fault alarm	Low power consumption, high reliability, suitable for humid environments
Food & Beverage	Mixers, transfer pumps, packaging machines	Frequent start-stop, hygiene standards, precise control	Long mechanical life (10 million cycles), IP20 protection
Automotive Manufacturing	Conveyors, hydraulic pumps, cooling fans	Interlock control, status feedback, fast response	2NO+2NC contacts for complex control logic
Textile & Dyeing	Carding machines, dyeing equipment, dryers	Speed regulation, forward/reverse operation, overload protection	Compact structure, saves cabinet space
Building HVAC	Air conditioning compressors, cooling tower fans	Energy-saving control, remote monitoring, standby switching	Low holding power (3.8W), reduces operational costs
New Energy	PV inverters, energy storage systems, charging piles	Power switching, overload protection, signal feedback	Multiple certifications, adaptable to outdoor conditions

Detailed Industry Application Cases

Case 1: 1+1 Standby Control System for 15kW Submersible Pumps in Wastewater Treatment Plant

Project Background

Phase II project of an urban wastewater treatment plant. Five aeration tanks are equipped with 15kW submersible pumps for 24-hour continuous aeration. The system requires automatic duty/standby switching and automatic alarm upon faults.

Equipment Configuration

Main units: 5 sets of 15kW 400V three-phase submersible pumps

Control components: S-T35 AC200V contactor + TH-T35 thermal overload relay + GV2P32 motor circuit breaker + Mitsubishi FX3U PLC

Auxiliary components: GVAE11 auxiliary contact block (status monitoring) + Audible & visual alarm + Manual/Auto selector switch

Solution Features

Redundant design: Independent control circuit for each pump to ensure uninterrupted operation
Status monitoring: 2NO+2NC contacts of S-T35 connect to PLC and alarm system for real-time status feedback
Energy saving: 18VA pull-in power and 3.8W holding power reduce energy consumption and cabinet temperature rise
Multi-level protection: Circuit breaker for short-circuit protection, thermal relay for overload protection and contactor for circuit breaking to ensure equipment safety

Application Results

Stable operation for 3 years with zero unplanned shutdown

Automatic switching time ≤ 2 seconds, meeting process continuity requirements

15% energy saving compared with traditional contactors

40% lower maintenance cost and high versatility of spare parts

Case 2: Temperature Control System for 18.5kW Centrifugal Fans in Food Processing Plant

Project Background

The sterilization workshop of a dairy plant needs to maintain a constant temperature of 120℃. Three 18.5kW centrifugal fans are deployed to automatically adjust operating quantity according to ambient temperature for energy saving.

Equipment Configuration

Main units: 3 sets of 18.5kW 400V three-phase centrifugal fans

Control components: 3 × S-T35 AC200V contactors + Temperature sensors + Mitsubishi PLC + HMI

Protection components: Moulded case circuit breaker + Thermal overload relay + Phase sequence protection relay

Solution Features

Graded control: Automatically run 1/2/3 fans according to temperature ranges (≤115℃ / 115-125℃ / ≥125℃)
Star-delta starting: Reduces inrush current; the contactor withstands high starting impulse current effectively
Visualization: HMI displays real-time operating status, current and temperature of each fan
Maintenance reminder: Cumulative runtime recording reminds users of regular contactor maintenance

Application Results

Temperature control accuracy improved to ±1℃, product yield increased by 3%

22% energy saving, saving approximately 120,000 RMB on electricity annually

Extended fan service life and reduced replacement frequency

Simplified operation with less manual intervention

Case 3: Conveyor Interlock Control System in Auto Parts Factory

Project Background

The assembly line of an automotive seat factory consists of 12 conveyors driven by 15kW motors. The system requires sequential start-up from feed end to discharge end, reverse sequence shutdown, and full-line shutdown protection once any conveyor fails.

Equipment Configuration

Main units: 12 sets of 15kW 400V three-phase conveyor motors

Control components: 12 × S-T35 AC200V contactors + Mitsubishi PLC + 6 emergency stop buttons + Safety relay

Signal system: 12 × GVAE11 auxiliary contact blocks (status feedback) + 24 indicator lights (operation/fault)

Solution Features

Interlock logic: PLC realizes interlock between conveyors via contactor auxiliary contacts to prevent material accumulation
Safety design: Emergency stop signal directly cuts off coil power of all contactors with response time ≤ 0.1 second
Fast fault diagnosis: Contactor status uploaded to PLC for quick fault location
Modular design: Unified model reduces spare parts inventory and maintenance costs

Application Results

Production line failure rate reduced by 60%, production capacity increased by 15%

Average fault troubleshooting time shortened from 45 minutes to 5 minutes

Improved operational safety with zero safety incidents

30% lower spare parts cost and higher maintenance efficiency

Case 4: Dual-motor Control System for Carding Machine in Textile Mill

Project Background

Renovation of BEFAMA CRIII carding machine in a wool textile mill. The original 37kW wound rotor motor with large starting current is replaced by a 7.5kW + 11kW dual-motor drive (total power 18.5kW), requiring synchronous start and balanced load.

Equipment Configuration

Main units: 7.5kW + 11kW 400V three-phase dual motors

Control components: 2 × S-T35 AC200V contactors + Mitsubishi inverter + PLC + Current sensors

Protection components: 2 × thermal overload relays + Short-circuit protection circuit breaker

Solution Features

Load balancing: PLC monitors motor current via sensors and dynamically adjusts inverter output
Smooth start: Combined inverter and contactor reduces starting current from 68A to 28A and minimizes grid fluctuation
Energy-saving operation: Motor speed automatically adjusted according to load, 30% energy saved
Fault protection: Both contactors trip simultaneously if either motor is overloaded to avoid equipment damage

Application Results

Starting current reduced by 59%, eliminating grid fluctuation

30% energy saving, saving approximately 80,000 RMB on electricity annually

Extended equipment service life, maintenance cycle prolonged to 1 year

Improved product quality and wool sliver uniformity by 2%

Application Classification & Selection Guidelines

3.1 In-depth Analysis of Applicable Scenarios

Application Type	Specific Usage	Selection Advantages	Notes
Direct-on-line Starting	Small & medium pumps, fans, compressors (≤18.5kW)	40A rated current, perfect match for 18.5kW motors, long mechanical life	Must use with thermal overload relays; avoid over 1200 start-stop cycles per hour
Star-delta Starting	Reduced-voltage start for 15-30kW motors	2NO+2NC contacts meet control demands for main/star/delta contactors	Select S-T35 for main contactor, S-T20 for star/delta contactors
Duty/Standby Operation	Fire pumps, drainage pumps and critical equipment	Low power consumption, suitable for long-term standby	Add automatic switching circuit to ensure standby availability
Interlock Control	Production lines, conveyors and multi-motor systems	Abundant auxiliary contacts for complex logic	Match contactor mechanical life with system operating frequency
PLC Control	Automated production lines and intelligent systems	Auxiliary contacts work reliably under micro-load (20V, 3mA) matching PLC outputs	Install surge suppressor in control circuit to protect PLC output points

3.2 Not Recommended Scenarios & Alternatives

Unsuitable Scenario	Reasons	Alternative Solutions
Single-phase motor control	3-pole structure not applicable for single-phase circuits	Select 2-pole contactors (single-phase version of S-T35)
Over 1200 start-stop cycles per hour	Shortens electrical life (rated 1 million AC-3 cycles)	DC contactors or solid state relays
Altitude above 2000m	Reduced arc extinguishing capacity due to thin air	Derate by 10% per 1000m elevation, or select high-altitude dedicated models
Severe vibration (over 5g)	Risk of loose parts and false operation	Install shock-absorbing pads or vibration-resistant contactors
Corrosive & humid environments	IP20 protection fails to prevent contact oxidation	Add protective enclosure or select IP65 products
Direct starting for motors over 50kW	Excessive starting current damages contacts	Soft starters or inverters

Summary & Selection Recommendations

4.1 Application Value Summary

High Reliability: 10 million mechanical cycles and 1 million electrical cycles (AC-3 40A/400V) for long-term industrial operation

Cost Efficiency: Low power consumption (18VA pull-in, 3.8W holding) cuts operational cost and heat generation inside cabinets

Flexibility: 2NO+2NC auxiliary contacts support status monitoring, alarm and interlock functions

Good Compatibility: Matches GV2/GV3 motor circuit breakers and TH-T thermal overload relays to form a complete protection system

4.2 Selection Mnemonic

Ideal match for 18.5kW motors, S-T35 is your first choice

AC200V coil fits well, low power saves energy all the way

2NO plus 2NC contacts complete, for monitoring and alarm needs

IP20 solid protection, stable performance in industrial sites

4.3 Application Optimization Suggestions

Protection Matching: Equip with thermal overload relays (e.g. TH-T35) and motor circuit breakers for dual protection against overload and short circuit.
Installation Standard: Mount vertically (±15°); reserve sufficient heat dissipation space (10mm left/right, 20mm top/bottom).
Wiring Specification: 1.5-35mm² copper wire for main circuit (torque 6-8Nm); 0.5-1.5mm² copper wire for control circuit (torque 0.8-1.2Nm).
Maintenance Cycle: Inspect contacts every 6 months; replace frequently operated contactors annually.
High-temperature Adaptation: Derate 1% per ℃ when ambient temperature exceeds 40℃.