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Single-Phase Digital Meters: Reliable 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
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. 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
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True RMS Measurement โ Accurate voltage readings even with distorted waveforms caused by non-linear loads (e.g., switching power supplies, LED lighting).
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High-Visibility Digital Display โ Clear unit indication (V/kV) for quick on-site data verification.
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Overvoltage Indication โ Alerts 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
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
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High-Precision Linear Measurement โ Minimal drift, suitable for both steady-state and fluctuating DC voltage monitoring.
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Polarity Reversal Protection โ Prevents meter damage when connected with incorrect terminal polarity.
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Compact DIN-Rail / Panel-Mount Design โ 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
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
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Accurate RMS Current Measurement โ Configurable display scaling to match CT ratios for direct primary current indication.
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Overcurrent Alarm Function โ Notifies users of excessive current draw, helping prevent equipment overheating and damage.
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Standard CT Compatibility โ Enables easy system expansion and retrofitting with standard CT models.
Technical Parameters
| Function & Shape / Model | Measure & Display | Shape Code (Figure Inside โก) | Selected Additional Functions | ||||||||
| Current | Voltage | Frequency | โจ | โง | โฆ | โค | โฃ | Communication Interface: RS485 | 2-Channel Switch Output | 1-Channel Analog Output | |
| 96ร96 | 80ร80 | 72ร72 | 96ร48 | 48ร48 | |||||||
| SFS-โกK1-I | โ | โ | โ | ||||||||
| SFS-โกK1-U | โ | โ | โ | โ | |||||||
| SFS-โกK1-F | โ | โ | โ | โ | |||||||
| SFN-โกK1-I | โ | โ | โ | โ | โ | โ | |||||
| SFN-โกK1-U | โ | โ | โ | โ | โ | โ | |||||
| SFN-โกK1-F | โ | โ | โ | โ | โ | โ | |||||
| SFN-โกK1-I+RS | โ | โ | โ | โ | โ | + | |||||
| SFN-โกK1-U+RS | โ | โ | โ | โ | โ | + | |||||
| SFN-โกK1-F+RS | โ | โ | โ | โ | โ | + | |||||
| SFN-โกK1-I+2DO | โ | โ | โ | โ | โ | + | |||||
| SFN-โกK1-U+2DO | โ | โ | โ | โ | โ | + | |||||
| SFN-โกK1-F+2DO | โ | โ | โ | โ | โ | + | |||||
| SFN-โกK1-I+1AO | โ | โ | โ | โ | โ | + | |||||
| SFN-โกK1-U+1AO | โ | โ | โ | โ | โ | + | |||||
| SFN-โกK1-F+1AO | โ | โ | โ | โ | โ | + | |||||
โ = Primary measurement function ย |ย โ = Available shape code ย |ย + = Additional function included
Frequently Asked Questions (FAQ)
Q
What is the difference between the SFS series and the SFN series digital meters?
The SFS series supports fewer panel size options (96ร96 and 72ร72 only), while the SFN series is compatible with a wider range of enclosure sizes including 96ร96, 80ร80, 72ร72, 96ร48, and 48ร48. In addition, the SFN series supports optional add-on functions such as RS485 communication, 2-channel switch output (2DO), and 1-channel analog output (1AO), making it more suitable for advanced monitoring and automation applications.
Q
Do I need a voltage transformer (PT) to measure high-voltage AC systems?
Yes. For AC voltages exceeding 600 V, a voltage transformer (PT) with a standard secondary output of 100 V AC is required. The PT steps down the high primary voltage to a safe level for the meter while providing galvanic isolation to protect both the operator and the instrument. The displayed reading is automatically scaled according to the configured PT ratio to show the actual primary voltage.
Q
Can the digital AC ammeter measure currents above 10 A without a current transformer?
No. The direct measurement range of the digital AC ammeter is limited to 0 ~ 10 A AC. For currents exceeding 10 A โ up to 9999 A โ a current transformer (CT) with a standard secondary output of 5 A AC must be used. The ammeter display can be configured to show the primary current value directly based on the CT ratio selected (e.g., 100/5 A, 500/5 A, 1000/5 A).
Q
What does the RS485 communication interface option allow users to do?
The optional RS485 interface (available on SFN series models with the "+RS" suffix) enables the meter to communicate with SCADA systems, PLCs, data loggers, or building management systems using standard Modbus RTU protocol. This allows real-time remote monitoring of measured values, alarm status, and configuration parameters without requiring manual on-site reading.
Q
What is the purpose of the 2-channel switch output (2DO) and 1-channel analog output (1AO) options?
The 2-channel switch output (2DO) provides relay contact outputs that can be used to trigger alarms, control external devices, or activate protection circuits when a measured value exceeds a preset threshold (e.g., overcurrent or overvoltage alarm). The 1-channel analog output (1AO) provides a proportional 4โ20 mA or 0โ10 V signal corresponding to the measured value, which can be fed directly into a PLC analog input, data acquisition system, or chart recorder for continuous process monitoring.
Q
Is the digital DC voltmeter suitable for solar PV system monitoring?
Yes. The digital DC voltmeter with a direct measurement range of 0 ~ 600 V DC is well-suited for monitoring solar PV string output voltages, battery bank voltages, and DC bus voltages in solar inverter systems. Its high-precision linear measurement with minimal drift ensures reliable readings under fluctuating irradiance conditions, and its compact panel-mount design allows easy integration into PV combiner boxes and inverter control panels.