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Single-Phase Digital Meters from China Suppliers and Factory for Accurate AC/DC Measurement
Product Overview
1
Digital AC Voltmeter
1.1 Measuring Range & Configuration
The single-phase digital AC voltmeter offers two flexible measurement modes to accommodate low-voltage and ultra-high-voltage (UHV) single-phase AC systems:
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Direct Measurement Range: 0 ~ 600 V AC
This range supports direct connection to standard single-phase AC systems (e.g., 120 V, 220 V, 230 V, 240 V, 400 V, 600 V) without external signal conditioning equipment. It is ideal for on-site monitoring of lighting circuits, small appliance power supplies, and light industrial load systems. -
Extended Measurement Range (With Accessory Voltage Transformer - PT): 0 ~ 9999 kV AC
For high-voltage (HV) and UHV single-phase AC system monitoring (e.g., transmission lines, substations), the voltmeter is paired with a voltage transformer (PT) calibrated to a standard secondary output of 100 V AC. The primary voltage range (0 ~ 9999 kV) is determined by the PT ratio (e.g., 110 kV/100 V, 500 kV/100 V). The PT provides galvanic isolation between the high-voltage primary circuit and the voltmeter, ensuring operator safety and protecting the meter from overload damage.
1.2 Core Measurement Features
- True RMS measurement algorithm, ensuring accurate voltage readings even with distorted waveforms caused by non-linear loads (e.g., switching power supplies, LED lighting).
- High-visibility digital display with clear unit indication (V/kV) for quick on-site data verification.
- Overvoltage indication function to alert users of abnormal voltage conditions in the monitored system.
2
Digital DC Voltmeter
2.1 Measuring Range
The single-phase digital DC voltmeter is engineered for direct measurement of DC voltage systems, with no need for external auxiliary devices for the specified range:
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Direct Measurement Range: 0 ~ 600 V DC
This range covers common single-phase DC applications, including battery banks, DC motor drives, solar PV system outputs, and DC power supply units. The direct connection design simplifies installation and eliminates signal loss associated with auxiliary transformers.
2.2 Core Measurement Features
- High-precision linear measurement with minimal drift, suitable for both steady-state and fluctuating DC voltage monitoring.
- Polarity reversal protection to prevent meter damage when connected with incorrect terminal polarity.
- Compact DIN-rail or panel-mount design for seamless integration into control panels and electrical enclosures.
3
Digital AC Ammeter
3.1 Measuring Range & Configuration
The single-phase digital AC ammeter supports two measurement configurations to meet low-current and high-current single-phase AC system monitoring needs:
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Direct Measurement Range: 0 ~ 10 A AC
This range is ideal for direct connection to low-current single-phase AC circuits (e.g., lighting systems, small fans, control circuits), eliminating the need for external current transformers (CTs) and reducing installation complexity. -
Extended Measurement Range (With Accessory Current Transformer - CT): 0 ~ 9999 A AC
For high-current single-phase AC system monitoring (e.g., large industrial motors, welding equipment, distribution feeder currents), the ammeter is integrated with a current transformer (CT) rated for a standard secondary output of 5 A AC. The primary current range (0 ~ 9999 A) is defined by the CT ratio (e.g., 100 A/5 A, 500 A/5 A, 1000 A/5 A). The CT isolates the ammeter from high primary currents, preventing overload damage and ensuring measurement precision.
3.2 Core Measurement Features
- Accurate RMS current measurement, with support for configurable display scaling to match CT ratios for direct primary current indication.
- Overcurrent alarm function to notify users of excessive current draw, helping to prevent equipment overheating and damage.
- Compatibility with standard CT models, enabling easy system expansion and retrofitting.
Technical Parameters
| Function & Shape / Model | Measure & Display | Shape Code (Figure Inside □) | Selected Additional Functions | ||||||||
| Current | Voltage | Frequency | ⑨ | ⑧ | ⑦ | ⑤ | ④ | Communication Interface: RS485 | 2-Channels Switch Output | 1-Channel Analog Output | |
| 96×96 | 80×80 | 72×72 | 96×48 | 48×48 | |||||||
| SFS-□K1-I | ● | √ | √ | ||||||||
| SFS-□K1-U | ● | √ | √ | √ | |||||||
| SFS-□K1-F | ● | √ | √ | √ | |||||||
| SFN-□K1-I | ● | √ | √ | √ | √ | √ | |||||
| SFN-□K1-U | ● | √ | √ | √ | √ | √ | |||||
| SFN-□K1-F | ● | √ | √ | √ | √ | √ | |||||
| SFN-□K1-I+RS | ● | √ | √ | √ | √ | + | |||||
| SFN-□K1-U+RS | ● | √ | √ | √ | √ | + | |||||
| SFN-□K1-F+RS | ● | √ | √ | √ | √ | + | |||||
| SFN-□K1-I+2DO | ● | √ | √ | √ | √ | + | |||||
| SFN-□K1-U+2DO | ● | √ | √ | √ | √ | + | |||||
| SFN-□K1-F+2DO | ● | √ | √ | √ | √ | + | |||||
| SFN-□K1-I+1AO | ● | √ | √ | √ | √ | + | |||||
| SFN-□K1-U+1AO | ● | √ | √ | √ | √ | + | |||||
| SFN-□K1-F+1AO | ● | √ | √ | √ | √ | + | |||||
Frequently Asked Questions (FAQ)
Q
What is the difference between the SFS and SFN series models?
The SFS series supports fewer panel sizes (96×96 and 72×72), while the SFN series is compatible with a wider range of enclosure sizes including 96×96, 80×80, 72×72, 96×48, and 48×48. The SFN series also supports optional additional functions such as RS485 communication, 2-channel switch output, and 1-channel analog output.
Q
Do I need an external voltage transformer (PT) to measure high-voltage AC systems?
Yes. For AC voltages exceeding 600 V — particularly in high-voltage (HV) and ultra-high-voltage (UHV) systems such as substations and transmission lines — an external voltage transformer (PT) with a standard secondary output of 100 V AC is required. The PT provides galvanic isolation and ensures operator safety while allowing accurate primary voltage measurement up to 9999 kV.
Q
Can the digital AC ammeter measure high currents directly without a current transformer (CT)?
The digital AC ammeter supports direct measurement only up to 10 A AC. For higher current applications — such as large industrial motors or distribution feeders — an external current transformer (CT) with a standard secondary output of 5 A AC is required. The CT ratio determines the primary current range, which can extend up to 9999 A AC.
Q
Does the digital DC voltmeter support solar PV and battery storage applications?
Yes. The digital DC voltmeter with a direct measurement range of 0 ~ 600 V DC is well-suited for solar PV system outputs, battery banks, DC motor drives, and industrial DC power supply units. Its polarity reversal protection also safeguards the meter during incorrect wiring situations.
Q
What communication and output options are available for the SFN series?
The SFN series offers three optional add-on functions: an RS485 communication interface (for SCADA/PLC integration using Modbus protocol), 2-channel relay switch output (for alarm or control triggering), and 1-channel analog output (4–20 mA or 0–10 V for process control systems). These are indicated by the suffixes +RS, +2DO, and +1AO respectively in the model number.
Q
Are these meters suitable for installation in standard electrical control panels?
Yes. All meters in both the SFS and SFN series are designed for panel-mount installation and are available in multiple standard cutout sizes (48×48 mm to 96×96 mm), making them compatible with most industrial control panels and electrical enclosures. The compact design and DIN-standard dimensions allow for seamless integration into new or existing installations.