OMRON H3BG-8 Star-Delta Solid-State Timer

สถานะ: ยกเลิก (ยกเลิกใน 1997). Legacy 8-pin dedicated solid-state timer for star-delta motor starting.

Core application: Timing control for star-delta reduced-voltage motor starting to switch from star (ย) to delta (ดี). No instantaneous contacts.

คำจำกัดความของรหัสโมเดล

H3BG: Star-Delta timer series

8: 8-pin base mounting (compatible with socket such as P2CF-8)

Derivative models:

H3BG-8-30: Special power supply variant

H3BG-8H: Version with auxiliary instantaneous NO contact

ข้อมูลจำเพาะที่สำคัญ

หลักการทำงาน

Upon power-up, the star contact closes immediately, putting the motor into star connection for starting. Once the preset star timing elapses, the star contact opens. After a short transfer safety interval, the delta contact closes and the motor switches to delta connection for normal operation. This design prevents short-circuit risks caused by simultaneous closure of star and delta contactors.

รุ่นทดแทนที่แนะนำ (OEM Recommended)

H3BG-8 → H3CR-G8L (Current active ออมรอน star-delta timer, 8-เข็มหมุด)

H3BG-8-30 → H3CR-G8L-30

⚠️ Note: Pin assignment is not fully identical; rewiring is required. Max star timing extended from 100s to 120s; transfer interval timing remains unchanged.

คู่มือการแก้ไขปัญหา (For Legacy Spare Parts)

1. No power indicator after energization: Check voltage at pins 2 & 7; input voltage ≥85% of rated value. Power reset requires power-off duration ≥0.5s.
2. Star contactor pulls in, but fails to switch to delta after timing: Aging of internal solid-state circuit (common failure for discontinued models), or insufficient transfer interval setting.
3. Contacts actuate but contactors do not switch: Inspect socket oxidation and pin contact quality. Do not exceed 5A resistive load for contacts.
4. การรีเซ็ตบ่อยครั้งโดยไม่ได้ตั้งใจ: Excessive voltage drop caused by inrush current during star-delta starting.

Distinction from H3BG-N8 (ความสับสนทั่วไป)

H3BG-8: Older discontinued model; H3BG-N8: Revised H3BG-N series star-delta timer, not identical hardware.

H3BG-8: Max star timing 100s; H3CR-G8L: Max star timing 120s.

Operating Principle of OMRON H3BG-8 Star-Delta Solid-State Timer

The H3BG-8 is a dedicated solid-state electronic star-delta timer. It integrates two independent timing circuits. Its core feature is the built-in star-to-delta transfer safety interval, which prevents phase short-circuit caused by simultaneous pull-in of star and delta contactors. It is not a general single-delay time relay.

Reset method: Power reset. A power-off duration ≥0.5s is required for full reset; the full timing sequence restarts upon re-energization.

Timing Sequence (3 ขั้นตอน)

1. เวที 1: เปิดเครื่อง, Star Starting Timing (t₁, Star Time)

Power is supplied to pins 2 และ 7 of the timer. The power circuit activates, the star output contact closes immediately, energizing star contactor KMY. The motor starts in star connection with reduced voltage, while the internal star timing circuit starts counting.

Panel selectable t₁: 5s /10s /50s /100s (4 ranges for legacy H3BG-8).

2. เวที 2: Star Timing Complete → Star Contact Opens, Transfer Interval Timing Starts (t₂, Transfer Time)

When star timing t₁ expires, the star output contact opens immediately and KMY de-energizes and drops out.

Delta contact will NOT close right away. แทน, the built-in transfer interval timer starts (t₂ selectable: 0.05 /0.1 /0.25 /0.5 /0.75 /1.0ส).

This transfer interval serves as a safety isolation window. It ensures the main contacts of the star contactor fully separate and arc extinguishes before the delta signal is output. This is the most critical function of star-delta timers.

3. เวที 3: End of Transfer Interval t₂ → Delta Output Contact Closes for Normal Operation

After transfer interval t₂ elapses, the delta output contact closes, energizing delta contactor KMD. The motor switches to delta connection for full-voltage continuous operation. The timer maintains this state until the whole system is powered off for reset.

⚠️ Basic H3BG-8 has no instantaneous contacts, only two timed NO contacts for star and delta. H3BG-8H is the variant with an extra instantaneous output.

Internal Circuit Architecture

Power supply circuit: AC100/110V or AC200/220V supply for oscillator timing circuits

Star timing oscillator & counter unit: Responsible for t₁ (motor star acceleration duration)

Transfer interval oscillator & counter unit: Independent t₂ safety gap timing

Output driver: Two separate SPST-NO relay contacts to control coil circuits of KMY and KMD

Indicators: Star run indicator, delta run indicator to show real-time status

Timing Sequence Diagram

Power ON → Star contact ON, motor star starting, t₁ timing → t₁ complete, star contact OFF → Wait for t₂ transfer interval → t₂ complete, delta contact ON, motor delta operation → Power OFF for reset

Key Design Notes (Field Commissioning for Legacy Equipment)

1. t₁: Star time: Match with motor rated power to allow sufficient speed rise. Too short causes heavy switching inrush; too long leads to continuous overheating of star contactor.
2. t₂: Transfer interval time: Do not set too low! At 0.05s setting, slow contactor release may easily cause phase short-circuit. For large motors, 0.25~0.5s is generally recommended.
3. Power reset: Brief voltage sag or momentary power dip will not trigger reset if power-off duration <0.5ส. The timer may skip star starting and directly enter delta mode after re-power, which is a common on-site fault.
4. Contacts only control contactor coils, cannot directly carry large motor main-circuit current. Contact rating AC250V 5A resistive.

Difference from General Time Relays

General time relay: Only one set of delayed contacts, no built-in transfer interval. Additional interlock circuit is mandatory, risking simultaneous pull-in of star and delta contactors and short-circuit.

H3BG-8: Dedicated star-delta timing logic. Dual timing hardware integrated, automatically executing sequence: star cut-off → wait safety gap → delta switch-on, simplifying control wiring.

Application Scenarios of OMRON H3BG-8 Star-Delta Solid-State Timer

The H3BG-8 is a dedicated star-delta reduced-voltage starting sequence controller, exclusively used for 3-phase asynchronous motor Y-Δ starting control. It automatically completes Y→Δ switching via built-in dual timing (star start delay + transfer safety interval). Core objectives: reduce motor starting inrush current and prevent short-circuit from overlapping actuation of star and delta contactors.

หมายเหตุ: รุ่นนี้เลิกผลิตแล้ว. It is used only as spare parts for legacy equipment retrofitting. H3CR-G8L is preferred for new projects.

1. สถานการณ์การใช้งานทั่วไป
2. Water Pump Sets (ที่พบบ่อยที่สุด)

ปั๊มหมุนเวียน, ปั๊มทำความเย็น, น้ำประปา & drainage centrifugal pumps, ปั๊มน้ำเสีย, mostly ≥15kW 3-phase motors.

Star-delta starting reduces water hammer for piping systems sensitive to large shock.

Operating profile: Continuous long-run operation, medium start-stop frequency.

2. แฟนๆ & ระบบระบายอากาศ

Large centrifugal fans, พัดลมร่างที่เกิดจากหม้อไอน้ำ, large air-handling unit fans, พัดลมดูดฝุ่น.

High inertia fans with load rising gradually with speed, well suited for Y-Δ starting.

Used in factory ventilation, HVAC and dust removal control cabinets.

3. เครื่องอัดอากาศ

Screw air compressors, piston air compressors (motor must have 6 winding terminals to support star-delta).

Reduce grid inrush to protect low-voltage distribution systems, widely deployed in small factory power cabinets.

4. กำลังลำเลียง & อุปกรณ์ผสม

สายพานลำเลียง, สกรูลำเลียง, เครื่องกวน, เครื่องผสม.

Gentle soft starting to avoid belt slipping, material impact and instantaneous stress damage to reducers.

5. เครื่องมือกล, Hydraulic Stations & Legacy Plastic/Rubber Machinery

Main motors for large hydraulic stations, เครื่องอัดรีด, เครื่องบด, vintage machine tools.

A large volume of imported and domestic control cabinets from the 1990s were factory-fitted with H3BG-8; now only for spare replacement.

6. Low-Voltage Power Control Cabinets for Small Factories

Factory low-voltage power cabinets, local MCC motor control boxes.

Where grid capacity is limited, direct-on-line starting causes voltage dip and light flicker; star-delta starting is adopted.

2. Application Prerequisites (บังคับ)
3. 3-phase asynchronous motor must have 6 winding terminals (U1/V1/W1, U2/V2/W2), rated operating connection is delta.
4. Motor operates under no-load or light-load starting; star-delta is only suitable for low starting torque demand. Not recommended for heavy-load start.
5. ควบคุมอุปทาน: AC100/110V or AC200/220V.
6. Control loop: Must work with 3 คอนแทคเตอร์ (main KM, star KMY, delta KMD) plus thermal overload relay.
7. การใช้งานที่ไม่เหมาะสม
8. Motors with only 3 terminals or factory-configured star connection for rated operation: cannot implement star-delta starting.
9. Heavy-load starting equipment (โรงสีลูกบอล, crushers with material load): insufficient starting torque from star connection.
10. Equipment requiring frequent start-stop cycles: H3BG-8 is power-reset type; frequent cycling accelerates aging of internal components.
11. ป้องกันการระเบิด, อุณหภูมิสูง, high-humidity or corrosive environments: H3BG-8 itself is non-explosion-proof; explosion-proof enclosure is required separately.
12. New design projects: Model discontinued; select H3CR-G8L instead.
13. Field Performance Characteristics

ข้อดี: Built-in transfer safety interval. Hardware-integrated safety gap simplifies control wiring and reduces phase short-circuit risk. General time relay solutions require extra electrical interlock.

ข้อจำกัด: Legacy solid-state circuitry. Timing drift and contact degradation are common after long service life; limited to spare replacement for existing installations.