Bluetooth
TOMZN Bluetooth Smart Timer Switch 85-265VAC 10A 30A EasyCon
Wall-Mounted
28 Groups
Loop Timing
Industrial Core Offerings
Precision Protection & Switching Products
Factory-direct photovoltaic protection components, intelligent DIN rail time control units, and surge mitigation modules manufactured in Liushi, Wenzhou.
35mm DIN
TOS6-40 Bluetooth Time Control Switch 35mm DIN Rail AC85-265V 40A
40A Rated
Countdown
Tomzn Brand
10-in-1 Relay
TORT7 Series Delay-ON Delay-OFF 10-in-1 Multi-Function Relay
0.1S-10D Range
Asymmetric Cycler
Pulse Gen
Smart Control
TOMZN TOS7-B Bluetooth Smart Timer Switch 40A 63A 85-265V
EasyCon App
Remote Control
63A Heavy Load
Programmable
TOMZN 1NO+1NC DIN Rail Weekly 7-Day Programmable Timer Switch
12V/24V/230V
16A Relay
LCD Display
New Design
TOMZN New Type Single Phase Weekly Digital Time Switch Relay
Compact Rail
Multi-Voltage
Anti-Interference
Solar Surge
OEM Photovoltaic DC SPD Surge Protector 500V-1000V 20-40kA
Class II / Type 2
Pluggable Cartridge
MOV Array
PV Combiner
Solar Photovoltaic PV String Combiner Box with Integrated SPD & MCB
IP65 Waterproof
Pre-Wired DC
Custom String
24+
Years in Manufacturing
5,700m²
Verified Floorspace
92
Technical Personnel
US$ 3.3M
Verified Annual Export
100+
Export Destinations
Engineering Fundamentals: Photovoltaic Surge Protective Devices (PV SPDs)
In modern commercial, industrial, and utility-scale solar generation, transient overvoltages represent the single greatest cause of catastrophic inverter failure, yield degradation, and fire risk. Photovoltaic strings operate under extreme direct current (DC) conditions where persistent open-circuit voltages ($V_{oc}$) lack natural zero-crossing points. Consequently, standard AC arresters cannot extinguish arcs once conduction occurs, creating thermal runaways. Selecting custom OEM PV Surge Protective Devices (SPDs) compliant with IEC 61643-31 and EN 50539-11 standards is paramount for solar EPC contractors, original equipment manufacturers, and system integrators.
Key Engineering Metric: A compliant DC PV SPD must feature a Maximum Continuous Operating Voltage ($U_{cpv}$) rated at least 1.2 times the maximum temperature-adjusted array open-circuit voltage ($1.2 \times V_{oc(max)}$) and incorporate a rapid-response galvanic thermal disconnection system to eliminate catastrophic DC arcing at end-of-life.
MOV Nanocrystalline Discs and Dynamic Thermal Disconnection
High-reliability DC surge arresters engineered by Zhejiang TMB Electric Co., Ltd. utilize high-density Zinc Oxide ($\text{ZnO}$) Metal Oxide Varistors (MOVs) paired in symmetric Y-topologies (DC+, DC-, PE). Under nominal operation, the varistor exhibits micro-ampere leakage currents. When lightning strikes or switching transients induce kilovolt surges across the array, the MOV shifts to low-impedance conduction within less than 25 nanoseconds, discharging tens of kilo-amperes safely into ground before clamping residual voltage ($U_p$) below inverter breakdown thresholds.
High Discharge ($I_{max} \le 40\text{kA}$)
Heavy-duty Class II MOV configuration capable of withstanding repetitive high-energy transients without dynamic degradation.
<25ns Fast Clamping
Ultra-fast response time effectively suppresses inductive lightning transients before sensitive MPPT bridge circuits are stressed.
Dual Thermal Disconnector
Patented low-temperature eutectic solder alloy decouples compromised cartridges safely, preventing DC flashovers.
Remote Signal Monitoring
Dry contact auxiliary output terminals provide real-time status relays to SCADA systems and monitoring dashboards.
Technical Matrix: PV Surge Protector Specifications (DC Type 1 & Type 2)
Specifying custom OEM assemblies requires exact alignment with inverter topologies, string voltage calculations, and local grid interconnection codes:
| Electrical Parameter | Residential String (600V DC) | Commercial C&I (1000V DC) | Utility Scale (1500V DC) | Standard Compliance |
|---|---|---|---|---|
| Max. Continuous Voltage ($U_{cpv}$) | 600V DC | 1000V – 1200V DC | 1500V DC | IEC 61643-31 / EN 50539-11 |
| Nominal Discharge ($I_n$, 8/20μs) | 15 kA – 20 kA | 20 kA | 20 kA – 30 kA | Class II / Type 2 Test |
| Max. Discharge ($I_{max}$, 8/20μs) | 40 kA | 40 kA | 50 kA | UL 1449 4th Ed. / CE |
| Impulse Current ($I_{imp}$, 10/350μs) | N/A (Type 2) | 6.25 kA (Type 1+2 Option) | 12.5 kA (Type 1) | Class I Lightning Arrester |
| Voltage Protection Level ($U_p$) | ≤ 2.5 kV | ≤ 3.6 kV | ≤ 4.5 kV | At Nominal $I_n$ Threshold |
| Short-Circuit Rating ($I_{scpv}$) | 1,000 A | 1,000 A | 2,000 A (No Back-up Fuse) | Galvanic Disconnect Test |
Global Procurement Trends & Technological Evolution in PV Protection
As the solar industry transitions from early subsidies to unsubsidized Levelized Cost of Energy (LCOE) parity, procurement criteria have matured significantly. System developers and balance-of-system (BOS) procurement managers no longer assess components purely by purchase price; instead, component longevity, localized field serviceability, and integrated diagnostics dominate the evaluation lifecycle.
1. Mass Shift to 1500V Architecture
Global utility developments have largely standardized on 1500V DC string topologies to minimize cabling resistive losses. OEM suppliers must manufacture SPDs with widened creepage distances, high tracking-index plastics, and multi-stage arc suppression chambers to prevent phase-to-ground flashovers.
2. Pre-Wired Combiner Box Assemblies
Severe skilled labor shortages across European and North American installation sites have propelled demand for turnkey, factory pre-wired combiner and junction boxes. Sourcing complete enclosures that integrate DC breakers, fuses, and pluggable SPDs directly slashes on-site commissioning errors by up to 65%.
3. Smart Diagnostic IoT Interfacing
Traditional mechanical green/red visual indicators require physically intensive manual site inspections. Next-generation SPDs are increasingly paired with intelligent DIN-rail telemetry modules (such as our Bluetooth and WiFi smart relays) to broadcast surge hit counters and varistor health status directly to cloud monitoring software.
Supply Chain Optimization: The Liushi Cluster Advantage
Sourcing directly from verified manufacturers located in Liushi, Wenzhou—the acknowledged epicentre of China's low-voltage electrical industry—provides measurable competitive moats. Within a five-kilometer radius, precision tooling, stamped silver-alloy contacts, flame-retardant polyamide enclosures, and zinc-oxide varistor chemistry are co-located. This dense vertical integration shortens prototype turnaround cycles from months to days and buffers overseas distributors against global raw material volatility.
Enterprise Capability: Zhejiang TMB Electric Co., Ltd.
Founded with a focus on mission-critical low-voltage protection, Zhejiang TMB Electric Co., Ltd. provides robust manufacturing capabilities for solar energy distributors, electrical panel builders, and international trading brands. Our verified facilities in Liushi Town, Wenzhou, combine automated injection molding, precision contact stamping, and computerized trip/surge testing lines.
Why Tier-1 Solar Distributors Partner With TMB
We provide full-spectrum engineering support from initial CAD concept and terminal configuration to complete CB, CE, and TÜV documentation packs.
- TÜV Rheinland Assessed: Comprehensive on-site factory verification covering 5,700 m² floorspace and certified quality management systems.
- Agile MOQ Flexibility: Low volume trial support (standard catalog items starting from 1 to 5 pieces) paired with container-scale production capacity.
- Complete DC/AC Ecosystem: Unified single-source procurement for DC SPDs, DC MCBs (up to 1000V/125A), DC MCCBs, PV Combiner Boxes, and Automatic Transfer Switches.
- End-to-End Private Labeling: Custom shell laser marking, customized terminal labels, bespoke packaging, and specific electrical trip curve calibrations.
Procurement FAQ: Technical & Operational Inquiries
Detailed engineering and export answers formulated according to Google E-E-A-T search intent standards for electrical engineers and procurement directors.
What is the difference between an AC SPD and a Photovoltaic DC SPD?
An AC surge protector is designed for systems where the alternating voltage naturally passes through zero 100 or 120 times per second, which allows the device to extinguish follow-current arcs easily. Photovoltaic DC circuits deliver constant, high-energy direct current with no natural zero-crossing. A DC PV SPD features specialized high-temperature arc-quenching chambers, larger internal separation distances, and thermal disconnect mechanisms designed specifically to safely extinguish sustained DC arcs at up to 1000V or 1500V DC without catching fire.
How do I calculate the correct voltage rating ($U_{cpv}$) for a solar array surge protector?
To calculate the minimum required $U_{cpv}$, identify the PV string's Open Circuit Voltage ($V_{oc}$) at Standard Test Conditions (STC). Factor in the site's historical lowest ambient temperature using the module's negative temperature coefficient of open-circuit voltage ($\beta V_{oc}$) to find $V_{oc(max)}$. Multiply $V_{oc(max)}$ by a safety safety factor of at least 1.1 to 1.2 ($U_{cpv} \ge 1.2 \times V_{oc(max)}$). For example, a system with a maximum calculated string voltage of 820V DC requires at least a 1000V DC rated SPD.
Does a DC SPD require upstream backup fuse or circuit breaker protection?
Yes, in accordance with IEC 61643-31 guidelines, an SPD must be coordinated with dedicated short-circuit overcurrent protection unless the device's certified short-circuit rating ($I_{scpv}$) exceeds the prospective short-circuit current of the solar generator at the point of installation. In combiner boxes, dedicated DC gPV fuses or high-breaking capacity DC miniature circuit breakers (DC MCB) are installed upstream to isolate a failed or shorted MOV module safely from the live DC array.
What OEM / ODM customization options are provided by Zhejiang TMB Electric Co., Ltd.?
We provide full-scope original equipment manufacturing, including laser-etched private branding, customized outer color housings, bespoke terminal configurations, integrated auxiliary remote contacts, specialized packaging, and pre-configured combiner box assemblies with custom string counts (1-in/1-out up to 16-in/1-out) integrated with MCBs, SPDs, and monitoring relays.
What testing reports and international compliance certificates accompany orders?
Every production batch undergoes 100% dielectric withstand, varistor clamp voltage ($U_v$), and micro-leakage current verification before leaving our Liushi factory. Official CE declaration of conformity, CB test reports, RoHS material compliance certificates, and our third-party on-site factory verification report from TÜV Rheinland are available to our B2B trade partners upon request.
Ready to Secure Your Solar DC Protection Supply Chain?
Connect directly with our engineering and export sales department in Liushi, Wenzhou. Request full electrical data sheets, customized OEM quotations, or sample evaluation units for your upcoming solar PV installations.
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