Product Updates · 2025-03-28
BDTY Single-Phase SCR Voltage Regulator: Signal Options, Sizing and Installation
Control signal options, current sizing from 10A to 400A, wiring and isolation practice, thermal design and commissioning steps for the BDTY single-phase SCR power regulator used on resistive heating loads.
The BDTY series is a single-phase SCR power regulator for resistive heating loads. Instead of switching a heater on and off, it uses phase-angle control to deliver a continuously variable fraction of line power, which removes the temperature ripple that on/off control produces on fast-responding heaters. Ordering data is on the BDTY product page.
1. Specification
| Parameter | Specification |
| Series / model | BDTY Series, BDTY-220D |
| Current options | 10A / 25A / 40A / 60A / 80A / 100A / 120A / 150A / 200A / 300A / 400A |
| Load voltage | 220VAC |
| Control signal | 0–10V / 4–20mA / 1–5V / 10kΩ potentiometer |
| Control type | Phase-angle SCR power regulation |
| Isolation | Opto-isolated signal and power circuits |
| Load type | Single-phase resistive |
| Typical applications | Heating equipment, ovens, packaging machines, plastic machinery |
2. Choosing the control signal
| Parameter | Specification |
| 4–20mA | Preferred in electrically noisy plant and for cable runs over a few metres; a broken wire reads as 0 mA and is detectable. |
| 0–10V / 1–5V | Direct connection to most PLC analog output cards. Keep cable short and screened. |
| 10kΩ potentiometer | Manual power control from a panel knob when no controller is used. |
The signal and power circuits are opto-isolated, but the signal cable should still be screened and routed away from the load cabling.
3. Sizing the regulator
- Steady-state current on a single-phase resistive load: I = P / V. A 6 kW heater at 220 VAC draws about 27 A.
- Choose the next rating with margin — the 27 A example needs the 40A model, not the 25A.
- Derate for high cabinet ambient, continuous duty and restricted airflow.
- Phase-angle control produces harmonic current; confirm supply cabling and protection are suitable, and consider zero-cross control where harmonics are a concern.
4. Installation
- Mount vertically with unobstructed airflow over the heat sink; the larger ratings need forced-air cooling.
- Fit upstream short-circuit protection sized to the module; semiconductor fuses give the best device protection.
- Torque all power terminals to specification and re-check after the first thermal cycle.
- Keep control wiring in a separate trunking from load wiring throughout the panel.
5. Commissioning
- With the heater isolated, apply minimum signal and confirm zero output; ramp to maximum and confirm a smooth rise with no steps.
- Verify that the output tracks the controller demand across the working range, not just at the extremes.
- Measure heat sink temperature after 30 minutes at full load and revise cooling if it is close to the derating limit.
- For closed-loop control, pair with a PID controller ordered with 4–20mA output and re-run auto-tune, because loop dynamics differ completely from on/off control.
6. FAQ
How is BDTY different from a solid state relay?
An SSR switches fully on or fully off. A BDTY regulator varies the conduction angle, producing continuously adjustable heating power.
Can it drive a three-phase heater?
No. Use the SCR3L or BSTY three-phase regulators.
Does it work with inductive loads?
The series is specified for resistive heating loads. Send us the load data before applying it to transformers or motors.
What size should I order for a 10 kW heater at 220 V?
About 45 A steady state, so the 60A model with margin for ambient and duty.
Sizing help: sales@strong-ele.com.