30+ Years of Precision Instruments
I. Overview: The ZK□-W3 SCR voltage regulator adopts single-chip computer technology and can switch online between phase-shift and zero-cross operating modes without changing the wiring, regulating the electric heating power on the load via unidirectional or bidirectional SCRs.
If phase-shift triggering is selected, the regulator changes the heating power by continuously changing the RMS value of each power waveform on the load. The advantage is that after the system stabilizes, the voltage on the load is low, significantly extending the service life of the heater; ordinary moving-coil meters can also be used to indicate load voltage and load current, with no sudden or flickering interference to the grid.
If zero-cross triggering is selected, the regulator changes the average heating power within a unit time (cycle time) by increasing or decreasing the number of complete power waveforms on the load within the unit time, regulating heating power in a pulsating manner. Since the SCR conducts slightly after the grid voltage crosses zero, switching loss and RF interference are small; however, moving-coil meters cannot be used to detect load voltage and current.
If the cold-state resistance of the load is extremely low but zero-cross control is required, the large current during initial heating may damage the SCR; in this case, the "manual" phase-shift output mode can be used for soft start. That is, first manually regulate with a small phase-shift current; once the load resistance increases with temperature to the current value allowed by the SCR, switch to zero-cross mode. This ensures system safety while achieving zero-cross control.
In summary, the ZK□-W3 SCR voltage regulator features strong versatility, wide adaptability, easy installation and reliable operation, and is widely applicable to high-precision automatic furnace temperature control of various electric heating furnaces.
II. Features: 1. The input can be switched to 0～10mA or 4～20mA according to the output format of the secondary instrument. Under all triggering modes, the load neutral line is allowed to be disconnected, fully reflecting the intelligent function of the single-chip computer product. 2. The regulator uses a high-brightness digital tube as the output indicator, easy to read from a distance, with good vibration resistance and strong anti-interference ability. 3. The "feedback" adjustment potentiometer is arranged on the panel; professionals can use it as "output limiting", improving regulation quality and safety margin. 4. If required, in the event of load short circuit or overcurrent, the instrument can automatically switch off the SCR trigger signal within 1～2 cycles, causing the SCR to cut off and avoid damage, while also providing load short circuit indication; the short circuit protection value is determined by the user's external current transformer (optional).
III. Main Technical Indicators: 1. Input signal: 0～10mA (impedance 800Ω); 4～20mA (impedance 250Ω), switched by a rear switch; 2. Output triggering mode: phase-shift or zero-cross (panel switch); 3. Output narrow pulse: three-phase six-channel trigger signal with amplitude ≥3V and output width ≥50μs; 4. Output pulse width without neutral line: three-phase six-channel trigger signal of approx. 3800μs; 5. Phase-shift conduction angle: ≥150°; 6. Zero-cross trigger cycle time: 2s±0.5s; 7. Overcurrent protection current (special order): determined by the external current transformer specification (without a current transformer, there is no overcurrent protection function); 8. Working power: default AC 220V±15% 50Hz±1Hz, approx. 10VA; other voltages such as AC 380V must be declared at order time
Special note: the working power supply of the regulator must be exactly consistent with the power supply of the controlled load. Each phase must be wired strictly according to the phase sequence specified in the diagram; otherwise, phase inconsistency may cause a phase load voltage to fail to fully turn on or output jitter.
IV. Product Models, Dimensions and Features. Dimensions are W×H×D (mm). Model / Overall Dimensions / Cutout Dimensions / Features: ZK-W3 160×80×130 152×76 horizontal, matched with XMT-19□, XMT-79□, XT-79□□ instruments; ZKS-W3 80×160×130 76×152 vertical, matched with XMTS-79□□, XT-79□□ instruments; ZKA-W3 96×96×130 92×92 IEC recommended dimensions, matched with XMTA-79□□, XTA-79□□ instruments; ZK□-W3t / / used in systems with three unidirectional SCRs and three diodes each reverse-parallel
