Products

넳 넲

Classification

Company Culture  ꄲ  Power Transmission  ꄲ  Siemens Vacuum Contactor | 3TL7125-0AL20-1A-ZF20 | 24kV 800A | 3-Pole
ꁆ ꁇ

Siemens Vacuum Contactor | 3TL7125-0AL20-1A-ZF20 | 24kV 800A | 3-Pole

Siemens 3TL7125-0AL20-1A-ZF20 medium voltage vacuum contactor, rated voltage 24kV, rated current 800A, 3-pole, electromagnetic operating mechanism, vacuum interrupter, chopping current <5A, mechanical endurance 1 million cycles, electrical endurance 0.5 million cycles, 4NO+4NC auxiliary contacts with insulating plate, AC/DC operation, IP00 open construction, for frequent MV motor starting, transformer, capacitor and reactor switching. Order available.
online consultation

Product Details

1. Product Overview

The Siemens 3TL7125-0AL20-1A-ZF20 is a Medium Voltage Vacuum Contactor from Siemens' 3TL71 series, with rated voltage 24kV and rated current 800A, three-pole, adopting electromagnetic operating mechanism and vacuum interrupter, specifically designed for high-frequency operation loads in medium voltage switchgear, suitable for three-phase motor starting, motor plugging/reversing, transformer switching, reactor switching, resistive load (such as electric furnace) switching, and capacitor bank switching applications.

In industrial power distribution systems, medium voltage motors (such as large water pumps, fans, compressors, mills, conveyors, etc.) require frequent start-stop operations. Traditional air contactors or oil-immersed contactors generate arcs when breaking current, which erodes contacts leading to short contact life, frequent maintenance, and limited breaking capacity. Vacuum contactors use vacuum interrupters as the arc-quenching medium, where contacts break current in a high vacuum environment (approximately 10⁻⁴ Pa). With almost no gas molecules in the vacuum environment, the arc extinguishes rapidly at current zero, resulting in minimal contact erosion. Therefore, vacuum contactors offer significant advantages such as long electrical life, high operating frequency, strong breaking capacity, compact size, no fire or explosion hazard, and low maintenance workload, making them particularly suitable for frequent start-stop operations of medium voltage motors.

The 3TL71 series vacuum contactors adopt vacuum switching technology, which has been developed and proven by Siemens for over 40 years, with mature and reliable technology. The vacuum interrupters constitute the medium-voltage part of the contactor, while the operating mechanism, closing latch, and control unit constitute the low-voltage part. The 3TL71 adopts a top-bottom arrangement structure (medium-voltage part and low-voltage part arranged vertically), different from the front-back arrangement structure of the 3TL61/65/68 series. The 3TL71 operates the vacuum interrupters via a linear mechanical connection (rather than the rocker structure of the 3TL61 series), and adopts a special double-coil electromagnet drive system designed for the closing and holding process.

The contactor's operating mechanism adopts electromagnetic drive with a special double-coil electromagnet (pick-up coil and holding coil), with pick-up power of 1200W and holding power of 200W (reference 230VAC). The electromagnet system is largely independent of voltage type and voltage level, supporting both AC and DC operation. The electronic module also assumes the economy circuit function, automatically switching to low-power holding mode after the contactor closes, reducing operating energy consumption and coil heating. The mechanical closing latch can hold the contactor in the closed position even after the electromagnet is de-energized, achieving electrical or mechanical opening via the latch release solenoid or mechanical trip lever.

The 3TL71 vacuum contactor can only be installed vertically (unlike the 3TL61/65/68 series which can be installed in any position). During installation, it is necessary to ensure that the vertical direction of the contactor aligns with the direction of gravity to ensure normal movement of the operating mechanism and correct operation of the vacuum interrupters.

In terms of chopping current, the 3TL71 series vacuum contactor has a chopping current of less than 5A. Chopping current refers to the current value at which the vacuum contacts forcibly interrupt the AC current before it naturally reaches zero when breaking AC current. The smaller the chopping current, the lower the switching overvoltage generated when breaking inductive loads (such as motors, transformers). Siemens vacuum contactors have a chopping current of less than 5A (the 3TL81 series even ≤0.6A), and do not generate impermissibly high overvoltages when switching accelerated motors during normal operation. However, when stopping high-voltage motors with starting currents ≤600A during startup, switching overvoltages may occur, which can be reduced to harmless values by configuring 3EF series overvoltage limiters (surge suppressors).

This contactor features high operating frequency and long life: mechanical endurance of 1 million operating cycles, vacuum interrupter mechanical endurance of 1 million operating cycles, electrical endurance (AC-1 utilization category, breaking rated normal current) of 0.5 million operating cycles, and switching frequency of 60 operating cycles/hour (without mechanical closing latch). These indicators are far higher than traditional air contactors, suitable for medium voltage motor applications requiring frequent operation, such as automatic control of water pumps, fans, compressors, and other equipment.

The auxiliary contact configuration of the 3TL7125-0AL20-1A is 4 normally open (NO) + 4 normally closed (NC), with insulating plate (order code suffix 1A indicates with insulating plate). The auxiliary contacts are positively driven structure, ensuring consistent action status between main contacts and auxiliary contacts, improving the reliability and safety of the control circuit. The auxiliary contacts are suitable for AC-14/15 and DC-13 utilization categories, and can be used for contactor status feedback, interlock control, signal indication, and other circuits.

In terms of short-circuit protection, 3TL vacuum contactors are designed to break load currents, not short-circuit currents, so short-circuit protection devices must be configured. The best protection method is HV HRC (High Rupturing Capacity) fuses, although circuit breakers can also be used. When using HV HRC fuses, the fuse melts rapidly before the short-circuit current reaches its peak, limiting the short-circuit current and protecting the vacuum contactor from overcurrent damage. Fuse selection must consider the load type (motor, transformer, capacitor) and coordinate with the contactor's overload protection characteristics.

This contactor complies with IEC 62271-100 standard (3TL71 series is based on this standard), with protection degree IP00 (open construction, designed for installation inside medium voltage switchgear), operating temperature range -40°C to +55°C (3TL71 series minimum operating temperature can reach -40°C, better than -25°C of 3TL61/65/68 series), storage temperature -25°C to +65°C, altitude range from 1250m below sea level to 5000m above sea level, shock resistance 10xg/5ms and 5xg/10ms, and design service life of 20 years.

Siemens 3TL series vacuum contactors are widely used in the following industrial applications: large water pump motor start-stop in water and wastewater treatment plants, fan/pump/coal mill motor control in power plants and thermal power plants, compressor/pump/fan motor start-stop in petrochemical plants, mill/crusher/conveyor/ventilation fan motor control in metallurgy and mining, mill/fan/compressor/conveyor motor control in cement and building materials industry, pump/fan/mixer motor control in paper industry, motor control in ships and offshore platforms, medium voltage capacitor bank switching (reactive power compensation), medium voltage transformer switching, medium voltage electric furnace and resistive load switching, medium voltage reactor switching, etc. In these applications, 3TL vacuum contactors ensure safe, reliable, and frequent operation of medium voltage motors and loads, reducing maintenance workload and improving system availability.

Note: This product 3TL7125-0AL20-1A-ZF20 is a Siemens 3TL71 series medium voltage vacuum contactor. The above technical parameters are from Siemens official 3TL vacuum contactor selection manual (HG 11.21, 2019 edition), with accurate and reliable parameters. The suffix ZF20 is a special configuration option, specific meaning subject to Siemens official factory configuration sheet; Contact via email for confirmation. Installation, wiring, and commissioning must be performed by professional engineers with medium voltage electrical operation qualifications, strictly following Siemens 3TL installation manual and medium voltage electrical safety operation procedures. The contactor must be installed inside medium voltage switchgear, configured with appropriate short-circuit protection (HV HRC fuses or circuit breakers), and insulation tests and operation tests must be performed before operation. Vacuum contactors can only be installed vertically, not tilted or horizontally.

2. Specifications

表格

Parameter Value
Brand Siemens (German multinational industrial group)
Product Series 3TL71 series medium voltage vacuum contactors
Model 3TL7125-0AL20-1A-ZF20
Product Type Medium Voltage Vacuum Contactor
Number of Poles 3 (Three-pole)
Arc Quenching Medium Vacuum (Vacuum interrupter)
Operating Mechanism Electromagnetic operating mechanism (double-coil electromagnet, pick-up + holding)
Rated Voltage Ur 24 kV
Rated Normal Current Ir 800 A
Thermal Current Ith 800 A (rated continuous normal current at ambient temperature up to +55°C)
Rated Operational Current Ie 630 A (according to AC-1/AC-2/AC-3/AC-4 utilization categories)
Rated Making Current Im 4500 A
Rated Breaking Current Ic 3600 A
Rated Short-circuit Breaking Current (limiting breaking capacity) Iba 7 kA
Rated Short-time Withstand Current (1s r.m.s.) Ik 8 kA
Rated Lightning Impulse Withstand Voltage (to earth/between phases) Up 125 kV
Rated Lightning Impulse Withstand Voltage (across open contact gap) Up 95 kV
Rated Short-duration Power-frequency Withstand Voltage (to earth/between phases) Ud 50 kV
Rated Short-duration Power-frequency Withstand Voltage (across open contact gap) Ud 50 kV
Chopping Current < 5 A
Mechanical Endurance (contactor) 1 million operating cycles
Vacuum Interrupter Mechanical Endurance 1 million operating cycles
Electrical Endurance (AC-1, breaking rated normal current) 0.5 million operating cycles
Switching Frequency (without mechanical latch) 60 operating cycles/hour
Rated Single Capacitor Bank Breaking Current Contact via email (subject to Siemens official data sheet)
Rated Capacitor Normal Current Contact via email (subject to Siemens official data sheet)
Rated Parallel Capacitor Bank Making Current Contact via email (subject to Siemens official data sheet)
Drive Solenoid Pick-up Power 1200 W
Drive Solenoid Holding Power 200 W (reference 230VAC)
Drive Solenoid Voltage Range 0.85 ~ 1.1 Ua
Operating Voltage Type AC/DC (supports both AC and DC operation)
Coil Rated Voltage Contact via email (subject to Siemens official factory configuration sheet, reference 110~250V AC/DC)
Latch Release Solenoid Power 100 W
Latch Release Solenoid Voltage Range 0.85 ~ 1.1 Ua
Closing Time 40 ~ 60 ms
Opening Time (without mechanical latch) 50 ~ 100 ms
Opening Time (with mechanical latch) ≤ 50 ms
Opening Time (with external circuit G01) ≤ 50 ms
Reclosing Time 100 ~ 180 ms and 50 ~ 75 ms
Auxiliary Contact Configuration 4NO + 4NC, with insulating plate (order code suffix 1A)
Auxiliary Contact Structure Positively driven
Auxiliary Contact Utilization Category AC-14/15, DC-13 (according to DIN EN 60947-1)
Auxiliary Contact Rated Current Contact via email (subject to Siemens official data sheet)
Mechanical Closing Latch Yes (standard configuration, can hold closed position after power loss)
Economy Circuit Yes (electronic module automatically switches to holding mode)
Trip-free Mechanism Yes (all contacts are trip-free, OPEN command takes priority over CLOSE command)
Mounting Method Vertical mounting only (3TL71 can only be installed vertically)
Installation Location Inside medium voltage switchgear
Protection Degree IP00 (open construction, according to IEC 60529)
Applicable Standard IEC 62271-100 (High-voltage alternating current contactors)
Operating Temperature -40°C ~ +55°C
Storage Temperature -25°C ~ +65°C
Altitude Range 1250m below sea level ~ 5000m above sea level
Shock Resistance 10 x g, 5ms; 5 x g, 10ms
Design Service Life 20 years
Short-circuit Protection Must be externally connected (recommended HV HRC fuses, circuit breakers also acceptable)
Overvoltage Protection Optional 3EF series overvoltage limiters (surge suppressors)
Suffix ZF20 Special configuration option, specific meaning Contact via email (subject to Siemens official factory configuration sheet)
Dimensions Contact via email (subject to Siemens official data sheet)
Weight Contact via email (subject to Siemens official data sheet)
Origin Contact via email (subject to Siemens official factory label)
Minimum Order Quantity 1 unit
HS Code Contact via email (reference 8536 or 8537)
Stock Status Order available
Warranty 12 months

5. Model Explanation

Model: 3TL7125-0AL20-1A-ZF20

Product Description: Siemens 3TL71 series medium voltage vacuum contactor, rated voltage 24kV, rated current 800A, 3-pole, electromagnetic operating mechanism, vacuum interrupter, 4NO+4NC auxiliary contacts with insulating plate, AC/DC operation, mechanical closing latch, IP00 open construction, for frequent MV motor starting and transformer/capacitor/reactor switching

3TL7125-0AL20-1A-ZF20 Configuration Overview:

  • 3TL = Siemens medium voltage vacuum contactor product series
  • 71 = Series code (24kV class, top-bottom arrangement, linear mechanical connection operation, double-coil electromagnet)
  • 25 = Specification code (24kV, 800A)
  • 0AL20 = Specific specification configuration (rated current, coil voltage, etc., subject to Siemens official configuration)
  • 1A = Auxiliary contact configuration: 4NO + 4NC, with insulating plate
  • ZF20 = Special configuration option suffix (specific meaning subject to Siemens official factory configuration sheet; Contact via email for confirmation)

Note: The meanings of each segment in the above model are inferred based on Siemens 3TL order code system. Specific naming rules and configuration are subject to Siemens official technical documentation and factory configuration sheet; Contact via email for confirmation.

3TL71 Series Main Specifications Reference:

表格

Model Series Rated Voltage Rated Current Mechanical Endurance Electrical Endurance Switching Frequency
3TL61 7.2kV 450A 3 million 1 million 1200/h
3TL65 12kV 400A 2 million 0.5 million 600/h
3TL68 15kV 320A 1 million 0.25 million 600/h
3TL71 24kV 800A 1 million 0.5 million 60/h
3TL81 7.2kV 400A 1 million 0.25 million 1200/h

Auxiliary Contact Configuration Options Reference (3TL71 series):

表格

Suffix Auxiliary Contact Configuration Description
0A 4NO + 4NC Standard
1A 4NO + 4NC With insulating plate — this model
5A 4NO + 4NC Transrapid

Related Products (ordered separately, Contact via email):

  • HV HRC fuses — for short-circuit protection
  • 3EF series overvoltage limiters (surge suppressors) — for switching overvoltage protection
  • Medium voltage switchgear (metal-clad) — for installing vacuum contactors
  • Control transformer — for contactor coil power supply
  • Auxiliary contact blocks (3SV9 series) — for expanding auxiliary contacts
  • Coil spare parts (3TY5 series) — maintenance spare parts
  • Vacuum interrupter spare parts — maintenance spare parts

Official Documentation Reference:

  • Siemens 3TL Vacuum Contactors Selection Manual (HG 11.21, 2019 edition)
  • Siemens 3TL Vacuum Contactors Installation and Operation Manual
  • Siemens 3TL71 Vacuum Contactor Technical Data Sheet
  • Siemens Medium Voltage Vacuum Switching Technology Guide (HG 11.01)
  • IEC 62271-100 High-voltage alternating current contactors standard

6. Why Choose Us

  1. Professional Procurement, Genuine Siemens Quality Guaranteed — All Siemens 3TL vacuum contactors and medium voltage electrical spare parts obtained through professional procurement channels, ensuring genuine Siemens original products, with product identification, factory inspection certificates, factory configuration sheets, and technical documentation, 12-month quality warranty. Pre-shipment appearance inspection, model confirmation, configuration verification, vacuum interrupter appearance check, operating mechanism manual operation test, auxiliary contact continuity test, insulation resistance test, and packaging check performed.
  2. Worldwide Delivery, Professional MV Heavy Equipment Logistics — DHL/FedEx/UPS international courier and sea/air freight available, global delivery available. Medium voltage vacuum contactors and other heavy industrial electrical equipment use shock-proof moisture-proof rust-proof professional packaging (wooden crate + foam cushioning + rust-proof bag + desiccant), ensuring safe transport. Expedited logistics and customs clearance available, delivery to 200+ countries, meeting urgent project and equipment maintenance needs.
  3. Professional Technical Support, MV Switchgear System Full-process Service — Vacuum contactor selection consultation (confirming rated voltage, rated current, operating frequency, load type, coil voltage, auxiliary contact configuration, short-circuit protection coordination, switchgear mounting dimensions), installation guidance (vertical mounting specifications, main circuit wiring, control circuit wiring, coil wiring, auxiliary contact wiring, grounding requirements, mechanical latch adjustment), system commissioning (close/open operation test, closing/opening time measurement, auxiliary contact status verification, interlock function test, insulation withstand voltage test), fault analysis (failure to close/open troubleshooting, coil burnout analysis, vacuum interrupter vacuum degree detection, auxiliary contact fault diagnosis, mechanical mechanism jamming handling, switching overvoltage analysis, spare parts replacement guidance), and MV switchgear system spare parts list review, helping users correctly select, install, commission, and maintain MV vacuum contactor systems.
  4. Flexible Procurement, Project Bulk and Spare Parts Framework Agreements — Single unit and bulk project orders, tiered discounts. Complete MV switchgear system package solutions available (vacuum contactor + HV HRC fuse + overvoltage limiter + control transformer + switchgear + technical service combination) and annual spare parts framework agreements, helping users optimize procurement cost, ensure spare parts supply, minimize equipment downtime risk. Customized quotations and long-term cooperation solutions available for water treatment, power, petrochemical, metallurgy, mining, cement, paper, marine, and other industry users.
  5. Pre-shipment Verification, Test Report Available — Appearance, packaging, model, configuration checks before shipment; vacuum contactor test report available if necessary (appearance inspection, model and silkscreen verification, factory configuration sheet verification, vacuum interrupter appearance check, manual operating mechanism test, close/open operation test, closing/opening time measurement, auxiliary contact continuity test, coil resistance measurement, insulation resistance test, mechanical latch function test, packaging check, accessory inventory), ensuring delivered product in good condition, parameters qualified, configuration correct. For urgent project needs (contactor fault replacement, plant maintenance, project commissioning, system modification and upgrade), priority inventory coordination and expedited shipping available.

7. Frequently Asked Questions (FAQ)

Q1: What is Siemens 3TL7125-0AL20-1A-ZF20? What are the main parameters?

A: Siemens 3TL7125-0AL20-1A-ZF20 is a Medium Voltage Vacuum Contactor from Siemens' 3TL71 series, with rated voltage 24kV, rated current 800A, three-pole, adopting electromagnetic operating mechanism and vacuum interrupter, specifically designed for high-frequency operation loads in medium voltage switchgear.

Core parameters: Brand Siemens, model 3TL7125-0AL20-1A-ZF20, product type medium voltage vacuum contactor, 3-pole, vacuum interrupter, electromagnetic operating mechanism (double-coil), rated voltage 24kV, rated normal current 800A, thermal current 800A, rated operational current 630A, rated making current 4500A, rated breaking current 3600A, limiting short-circuit breaking capacity 7kA, short-time withstand current 8kA/1s, lightning impulse withstand voltage 125kV (to earth) / 95kV (open gap), power-frequency withstand voltage 50kV, chopping current <5A, mechanical endurance 1 million cycles, electrical endurance (AC-1) 0.5 million cycles, switching frequency 60 cycles/hour, auxiliary contacts 4NO+4NC with insulating plate (suffix 1A), operating voltage AC/DC (reference 110~250V AC/DC), pick-up power 1200W, holding power 200W, closing time 40~60ms, opening time 50~100ms (without latch), mechanical closing latch yes, protection degree IP00, vertical mounting only, operating temperature -40°C~+55°C, standard IEC 62271-100, design life 20 years.

Main applications: MV three-phase motor starting and frequent start-stop (pumps, fans, compressors, mills, conveyors), motor plugging/reversing, MV transformer switching, MV reactor switching, MV resistive load (furnace) switching, MV capacitor bank switching (reactive power compensation).

Note: Vacuum contactors are designed to break load currents, not short-circuit currents, so short-circuit protection must be configured (recommended HV HRC fuses). 3TL71 series can only be installed vertically. The suffix ZF20 is a special configuration option, specific meaning subject to Siemens official factory configuration sheet; Contact via email for confirmation. Installation, wiring, and commissioning must be performed by professional engineers with MV electrical operation qualifications.

Q2: What is the difference between vacuum contactors and vacuum circuit breakers? How to choose?

A: Both vacuum contactors and vacuum circuit breakers use vacuum interrupters as the arc-quenching medium, but they differ significantly in design purpose, breaking capacity, operating frequency, structure, and price.

Vacuum Contactor features: 1. Design purpose: for frequent operation of loads such as motor starting, capacitor switching, transformer switching. 2. Breaking capacity: breaks load currents (several times rated current), limiting short-circuit breaking capacity is low (usually several kA to tens of kA), not designed to break short-circuit currents. 3. Operating frequency: high, up to tens to thousands of operations per hour. 4. Mechanical endurance: long, up to 1 to 3 million operations. 5. Electrical endurance: long, up to 0.25 to 1 million operations. 6. Structure: usually with electromagnetic or permanent magnet operating mechanism, compact structure, small size. 7. Short-circuit protection: must be used with HV HRC fuses, which handle short-circuit current breaking. 8. Price: relatively low. 9. Typical applications: frequent MV motor starting, frequent capacitor bank switching, electric furnace control.

Vacuum Circuit Breaker features: 1. Design purpose: for breaking short-circuit currents and fault currents, can also be used for normal load operation. 2. Breaking capacity: high breaking capacity, up to 20kA to 63kA or higher, capable of breaking short-circuit currents. 3. Operating frequency: low, usually several to tens of operations per day, not suitable for frequent operation. 4. Mechanical endurance: relatively short, usually 10,000 to 30,000 operations. 5. Electrical endurance: relatively short, limited number of rated short-circuit current breakings (usually several to tens of times). 6. Structure: usually with spring or permanent magnet operating mechanism, complex structure, larger size. 7. Short-circuit protection: self-contained short-circuit breaking capability, no additional fuses needed. 8. Price: relatively high. 9. Typical applications: MV distribution line protection, transformer incoming/outgoing protection, motor feeder protection (infrequent operation).

How to choose: 1. Motors requiring frequent operation (pumps, fans, compressors starting multiple times daily) → Select vacuum contactor + HV HRC fuses. 2. Distribution lines requiring short-circuit current breaking → Select vacuum circuit breaker. 3. Frequent capacitor bank switching (automatic reactive power compensation) → Select vacuum contactor. 4. Infrequent motor feeders (1-2 starts/stops daily, requiring short-circuit protection) → Can select vacuum circuit breaker or vacuum contactor + fuses. 5. Limited budget, frequent operation → Select vacuum contactor + fuses (overall cost lower than circuit breaker). 6. Require complete protection functions, infrequent operation → Select vacuum circuit breaker (with built-in protection relay). 7. Limited space, compact installation required → Select vacuum contactor (smaller size). 8. Require high operating frequency (>10 times/day) → Must select vacuum contactor.

Siemens 3TL7125-0AL20-1A-ZF20 is a 24kV/800A vacuum contactor, suitable for frequent MV motor starting and capacitor switching applications. If you need short-circuit current breaking or infrequent feeder protection, we recommend Siemens 3AH/3AE series vacuum circuit breakers. To confirm selection, please provide load type, rated voltage, rated current, operating frequency, short-circuit current level, switchgear dimensions, etc.; Contact via email, we can assist in confirming selection and short-circuit protection coordination 方案.

Q3: Why do vacuum contactors require HV HRC fuses? How to select fuses?

A: Vacuum contactors are designed to break load currents (such as motor starting current, capacitor inrush current, transformer magnetizing current), and their limiting short-circuit breaking capacity is low (3TL71 series is 7kA). They are not designed to break system short-circuit currents. When a short-circuit fault occurs in the system, the short-circuit current may reach tens of kA or even higher, far exceeding the breaking capacity of the vacuum contactor. If the vacuum contactor attempts to break the short-circuit current, it will cause severe erosion or even explosion of the vacuum interrupter, resulting in equipment damage and safety accidents. Therefore, vacuum contactors must be configured with HV HRC (High Rupturing Capacity) fuses as short-circuit protection, with the fuses handling the short-circuit current breaking task.

HV HRC fuse working principle: When a short-circuit current occurs, the fuse element melts in an extremely short time (usually a few milliseconds). During the melting process, a high arc voltage is generated, limiting the rise of short-circuit current (current-limiting characteristic), restricting the short-circuit current to a level far below the expected peak. The fuse completes breaking within the first half-cycle of current, protecting the vacuum contactor and other equipment from overcurrent damage. After the fuse operates, its striker triggers an auxiliary switch, which can 发出 an alarm signal or directly open the vacuum contactor.

Fuse selection principles: 1. Rated voltage matching: fuse rated voltage must be ≥ system rated voltage (24kV system selects 24kV fuses). 2. Rated current selection: fuse rated current must be ≥ motor normal operating current, and must consider the effect of motor starting current — the fuse's time-current characteristic must be located to the right of the motor starting current curve, ensuring the fuse does not operate during normal motor starting. 3. Breaking capacity: fuse rated breaking capacity must be ≥ system maximum short-circuit current. 4. Current-limiting characteristic: fuse let-through current must be ≤ maximum allowable let-through current of the vacuum contactor (3TL series maximum let-through current 50kA at 7.2kV). 5. Load type: motor loads, transformer loads, capacitor loads require different types of fuses (motor protection fuses, transformer protection fuses, capacitor protection fuses). 6. Coordination with contactor: the fuse's minimum breaking current must coordinate with the contactor's overload protection range — overload currents smaller than the fuse's minimum breaking current are broken by the contactor (via overload relay), and short-circuit currents larger than the fuse's minimum breaking current are broken by the fuse. 7. Striker configuration: recommend selecting fuses with strikers, which can trigger contactor opening or alarm when blown. 8. Fuse base: select matching fuse base, recommend configuring fuse trip indicators, which can 发出 alarm or open the contactor when one-phase fuse blows, preventing motor single-phase operation.

Fuse-contactor coordination notes: If low-voltage supply via control transformer, short-circuit currents above the limiting breaking capacity must be broken within 80ms (this requirement does not apply if mechanical latch is provided or opening times are extended). Motor starting current represents the maximum stress on the HV HRC fuse, and this stress must neither operate nor pre-damage the fuse-link. Other factors influencing fuse stress are starting time and starting frequency of the motors. If two fuse-links are connected in parallel, divide the determined symmetrical short-circuit current by two, and ensure the resistance values in the two branches are almost equal. After fuses operate, they must be replaced immediately, and vacuum contactors should be checked for vacuum interrupter condition after carrying maximum permissible symmetrical short-circuit current.

Siemens 3TL7125-0AL20-1A-ZF20 vacuum contactor must be configured with HV HRC fuses for short-circuit protection. Specific fuse model and parameters need to be calculated based on system voltage, motor power, starting current, short-circuit current level, etc.; Contact via email, we can assist with fuse selection and coordination calculations.

Q4: In stock? Lead time? Price?

A: Currently Order Available. Specific stock of Siemens 3TL medium voltage vacuum contactors fluctuates with market.

  • Lead time: Standard 6-10 weeks (3TL vacuum contactors are medium voltage heavy electrical equipment, some common specifications may be in stock, specific subject to formal quotation).
  • Price: Subject to formal quotation, depends on specific model specification, rated voltage and current, coil voltage, auxiliary contact configuration, special options (suffix ZF20), quantity, supply channel, whether includes technical service and on-site commissioning support, etc. Bulk procurement enjoys tiered discounts.
  • Package solutions: Complete MV switchgear system package solutions available (vacuum contactor + HV HRC fuse + overvoltage limiter + control transformer + switchgear + technical service combination), combined procurement price more favorable. If the project requires fuses and overvoltage limiters, it is recommended to purchase at the same time.
  • Expedited service: For urgent needs (contactor fault replacement, plant maintenance, project commissioning, system modification and upgrade), we can try to coordinate stock or expedited ordering, please contact sales team.
  • Please indicate: required quantity, desired delivery time and destination, system rated voltage and motor power, operating frequency and load type, coil voltage requirements, auxiliary contact configuration requirements, whether matching fuses and overvoltage limiters needed, whether installation commissioning and technical support services needed when inquiring; we will coordinate fastest delivery and optimal price.
ꄴPrevious： Kongsberg Dual Sensor Converter | GLB-7B/7A-SPARE-B | Marine Level Monitoring
ꄲNext： GE Multilin Motor Management System | MM300-GEHD1CABEXX | Low Voltage Motor Protection Relay