Editor's note: the Chinese body above is the complete transcript of DL/T 641-2005. This English text is an editorial summary prepared for international readers, not an official translation. Figures A.1/A.2/B.1 and the formula images were not preserved in the 2006 web version; the formulas have been re-typeset from their variable definitions in the standard text.
DL/T 641-2005 (replacing DL/T 641-1997), issued by the National Development and Reform Commission on 2005-02-14 and effective from 2005-06-01, specifies the terminology, types, technical requirements, selection, test methods, inspection rules, marking, packaging, transport and storage of electric actuators for power station valves (including their power control components). It applies to motor-driven electric actuators of various types for on-off valves, control (modulating) valves and dampers.
Construction: motor, gear reduction train, torque control (mechanical or electronic), travel control, position indication, position feedback (on request), manual operator, manual-electric changeover, power control (on request).
Service conditions: altitude up to 1000 m; ambient temperature -20℃ to +80℃ (on-off) or -20℃ to +60℃ (modulating); relative humidity up to 90% at 25℃; no strongly corrosive, flammable or explosive media. Supply: three-phase 380 V±10% or single-phase 220 V±10%, 50 Hz±1%.
General requirements (5.2): mounting dimensions to GB/T 12222/12223; earth terminal and marking; clockwise-to-close manual operation recommended; separation of power and control cabling; creepage and clearance distances per Table 1. Position indicator travel 80°–280° following the output shaft; position transmitter supply 12–30 V DC with 4–20 mA DC feedback within ±1% of span; noise ≤75 dB(A); insulation resistance ≥20 MΩ; dielectric test per Table 2.
Torque relations: maximum control torque ≥ rated torque; minimum control torque ≤ rated torque and ≤50% of maximum; setting torque between minimum and maximum (equals minimum if unspecified); locked-rotor torque > 1.1 × maximum control torque. Torque repeatability per Table 3; position repeatability per Table 4. Impact load resistance per Table 5. Life: 10,000 cycles without failure (on-off) / 200,000 cycles (modulating).
Modulating-duty requirements (5.3): intrinsic error ≤±1.0%, hysteresis ≤1.0%, dead band ≤1% of input span, damping ≤3 half-cycles; vibration test 10–150 Hz, 0.15 mm, 30 min with output signal change ≤±1%; after 48 h trouble-free running all above limits still hold.
| Table 1 Clearance and creepage distances | ||
|---|---|---|
| Rated voltage Ui (a.c. r.m.s.) V | Clearance mm | Creepage mm |
| ≤60 | ≥2 | ≥3 |
| 60 < Ui ≤ 250 | ≥3 | ≥4 |
| 250 < Ui < 500 | ≥4 | ≥6 |
| Table 2 Test voltages | |
|---|---|
| Rated voltage Ui (a.c. r.m.s.) V | Test voltage V |
| ≤60 | 500 |
| 60 < Ui ≤ 125 | 1000 |
| 125 < Ui ≤ 250 | 2Ui + 1000 |
| 250 < Ui ≤ 500 | 2Ui + 1000 |
| Table 3 Control-torque repeatability | |
|---|---|
| Actuator type | Torque repeatability |
| Multi-turn | ≤ ±7% |
| Part-turn | ≤ ±10% |
| Table 4 Position repeatability | |
|---|---|
| Actuator type | Position repeatability |
| Multi-turn | ±5° |
| Part-turn | ±1° |
| Table 5 Load requirement (impact) | |
|---|---|
| Max. control torque Nm | Load requirement |
| ≤ 4000 | 2 × max. control torque, or axially permissible thrust |
| ＞ 4000 | 1.8 × max. control torque, or axially permissible thrust |
Protection degree: indoors ≥IP55 (without mechanical brake) / IP54 (with brake); outdoors ≥IP65. Handwheel operating torque ≥15 Nm at maximum control torque. On-off actuators shall output open/closed/intermediate status signals, torque-overload signals in both directions, a remote flashing running signal, and a position signal (resistive or 4–20 mA DC). Modulating actuators shall additionally provide 4–20 mA DC position feedback with load capability ≥650 Ω and motor thermal protection. Actuators with power control component shall accept 4–20 mA DC (≤250 Ω), 24 V DC pulses (>300 ms) or contact signals (modulating) and contact/24 V DC signals (on-off), provide local/remote selection, anti-misoperation protection, overcurrent protection, hold-in-place on power loss, and hold or move to safe position on signal loss.
Intelligent actuators shall in addition offer: HMI-based parameter setting/commissioning/diagnostics, oscillation-free operation under all conditions (e.g. adaptive dead band), prevention of motor coasting, automatic three-phase phase-sequence correction, fail-in-place with fault signalling, emergency open/close operation, and a fieldbus interface to JB/T 10308.3.
Matching with valves: maximum control torque must exceed the torque required to open/close the valve in service; minimum control torque must be below it (for modulating service, not less than the running torque at mid-position); rated travel must cover the valve stroke and be adjustable. Double-speed valves require twin-motor, pole-changing or variable-frequency actuators.
Tests are run at rated voltage and frequency: IP test per GB 4208; visual checks; position indicator check over three full cycles; output signal check at 0/25/50/75/100% stroke with deviation Δo = (I1 − Io)/I × 100% (Eq. 1), three measurements per direction; noise per GB/T 3797; insulation resistance at 500 V DC; dielectric test per Table 2 held 1 min (1 s for sample inspection); no-load and loaded manual-electric changeover checks; maximum/setting/minimum control-torque tests (three per direction); locked-rotor torque test; torque repeatability δ0 = (Ms − Mz)/Mz × 100% (Eq. 2); travel position repeatability over three runs; strength test at Table 5 load ≥0.5 s; life test per Appendix A or B.
Modulating actuators: intrinsic error δ = (L1 − L0)/L × 100% (Eq. 3) measured on both increasing and decreasing signals; hysteresis from the maximum algebraic difference between up/down errors; dead band Δ = (I1 − I2)/I × 100% (Eq. 4) measured at 25/50/75% stroke; damping check with 25/50/75% step signals (≤3 half-cycles); resonance-search vibration test; 48 h stability run at 50% stroke with 20%–50% on-time factor at (580±50) operations/hour.
Every actuator undergoes factory inspection (Table 6). Sample inspection covers ≥3% of the batch; one failure doubles the sample and repeated failure forces 100% inspection. Type tests are required for new designs, major design/process/material changes, every 5 years in normal production, and on resumption after 5 years idle.
| Table 6 Inspection items | |||||
|---|---|---|---|---|---|
| No. | Inspection item | Inspection class | Requirement clause | ||
| Factory | Sample | Type | |||
| 1 | Enclosure protection test | — | — | √ | 6.1.2 |
| 2 | Appearance check | √ | √ | √ | 5.2.5–5.2.6 |
| 3 | Handwheel (lever) check | √ | √ | √ | 5.2.7 |
| 4 | Wiring and conductors check | √ | √ | √ | 5.2.8 |
| 5 | Creepage and clearance | — | — | √ | 5.2.9 |
| 6 | Position indicator check | √ | √ | √ | 5.2.10 |
| 7 | Output position signal check | — | √ | √ | 5.2.11 |
| 8 | Noise check | — | — | √ | 5.2.12 |
| 9 | Insulation resistance check | √ | √ | √ | 5.2.13 |
| 10 | Dielectric test | — | √ | √ | 5.2.14 |
| 11 | Manual/electric changeover check | √ | √ | √ | 5.2.15 |
| 12 | Max. control torque check | √ | √ | √ | 5.2.16 |
| 13 | Setting torque check | √ | √ | √ | 5.2.17 |
| 14 | Min. control torque check | √ | √ | √ | 5.2.16 |
| 15 | Locked-rotor torque check | √ | √ | √ | 5.2.18 |
| 16 | Torque repeatability check | — | √ | √ | 5.2.19 |
| 17 | Travel repeatability check | — | √ | √ | 5.2.20 |
| 18 | Strength test | — | — | √ | 5.2.21 |
| 19 | Life test | — | — | √ | 5.2.22 |
| 20 | Intrinsic error test | √ | √ | √ | 5.3.3 |
| 21 | Hysteresis test | — | — | √ | 5.3.4 |
| 22 | Dead band test | — | — | √ | 5.3.5 |
| 23 | Damping test | — | — | √ | 5.3.6 |
| 24 | Vibration test | — | — | √ | 5.3.7 |
| 25 | Long-run stability test | — | — | √ | 5.3.8 |
Nameplate (GB/T 13306) shall state: manufacturer; product name/model; maximum, minimum and setting torque; output speed (or travel time); stroke/turns; protection class; serial number; date. Exposed machined surfaces oiled; boxes rain-proof, stackable five-high; marking includes manufacturer, product, consignee, handling symbols, gross weight and volume. Each box carries the certificate, manual and packing list. Transport shall avoid violent shocks; storage in ventilated dry non-corrosive warehouses at -20℃ to +45℃, RH ≤85%.
Life = total open-stop-close-stop cycles until specified performance is lost. Running torque = 1/3 of maximum control torque (running at 1/3, closing at full torque; same for thrust). Cycle period 40 s: open 10 s, stop 10 s, close 10 s, stop 10 s. Fully open controlled by the travel switch, fully closed by the torque switch. 10,000 automatic cycles; efficiency measured via torque sensors before/after with η = output torque / input torque × 100% (Eq. A.1). Permissible changes per Table A.1.
| Table A.1 Permissible errors | ||
|---|---|---|
| Measured item | Measured parameter | Permissible error |
| Running efficiency | Input and output torque | ≤10% |
| Output torque | Torque | ≤10% |
| Travel control accuracy | Change of output-shaft open position | ≤±5° |
| Output signal error | Signal vs. final displacement error | ≤0.5% |
| Contact resistance | Resistance | ≤2 mΩ |
Life = total open-stop cycles until specified performance is lost. Running torque = minimum control torque, constant load. Cycle = one running period + one rest period, (300±30) cycles/hour, 25% duty factor. Direction controlled by the power control component. 200,000 automatic cycles (time-relay or 4–20 mA controlled); same measurement set and Table A.1 limits as Appendix A.
[1] Per GB 755: S2 — short-time duty; S4 — intermittent periodic duty with starting; S5 — intermittent periodic duty with electric braking.
