OMRON H3BA-8 Multi-Function Solid-State Timer

Classic legacy model, discontinued in 1997. Only used or stock spare parts available on the market.

Series: H3BA multi-mode solid-state timer, 8-pin round socket (compatible with MY relay base), multi-operation modes, wide time range with analog knob setting

1. Model Code Explanation

H3BA: Series name, multi-function solid-state timer

8: 8-pin round socket version (the 11-pin variant of the same series is H3BA without suffix 8)

Distinction: H3BA-8 ≠ H3BA-N8H (N8H is a later upgraded 8-pin model with partial functional differences)

2. Core Specifications
3. Operation Modes: 4 multi-function modes (A: On-delay, B: Flashing, OFF-initiated, B2: Flashing, ON-initiated, J: One-shot). Selectable via DIP switch on unit; self-reset, no external reset terminal.
4. Time Ranges (multi-range switchable)

0.05～1.2s / 1.2～12s / 0.12～1.2min / 1.2～12min / 0.12～1.2h / 1.2～12h, 6 selectable time units, continuously adjustable via knob.

3. Output Contacts: SPDT timed contact, resistive load AC250V 5A
4. Rated Supply Voltage: AC100/110V, AC200/220V, DC24V (defined by model suffix)
5. Accuracy: Voltage influence ≤±0.5%FS; temperature influence ≤±2%FS
6. Ambient Conditions: -10℃～+55℃, humidity 35～85% non-condensing
7. Mounting: Panel flush mounting. Matched with 8P round base (P3G-08 etc.), surface mounting also available.
8. Pin Assignment (8-pin round base, top view)

Standard MY relay compatible 8-pin base

Pin 2, 7: Power supply terminals

Pin 1, 3, 4: Timed SPDT contact (common / NC / NO)

Pin 5, 6, 8: Second set of timed SPDT contact (for some versions)

Note: Pin definition of legacy H3BA-8 is identical to newer H3CR-A8, critical for replacement.

4. Recommended Replacement Models (OMRON official recommendation)
5. Direct replacement: H3CR-A8 (8-pin multi-function, pin-compatible, full coverage of H3BA-8 functions, reuse existing base, most common upgrade solution)
6. If instantaneous contact required: H3CR-A8E
7. Domestic alternatives: 8-pin multi-function timers (e.g. ST3PA-B). Verify pinout and modes carefully.
8. Troubleshooting for second-hand spare parts inspection
9. Power indicator off after power-up: Check voltage on pin 2 & 7; inspect base contact and pin oxidation; internal power circuit failure (electrolytic capacitor aging is common failure for legacy units).
10. Inaccurate / drifting timing: Degraded internal electrolytic capacitor, the most frequent fault of old H3BA timers.
11. No contact switching upon timeout: Damaged internal solid-state trigger circuit or burnt contacts.
12. Failure to reset: Minimum power-off reset time ≥0.1s; rapid power cycle after power-off may cause reset failure.
13. False operation from interference: Separate power cables and timer control wires; install surge absorber.
14. Selection & Replacement Notes
15. Match supply voltage strictly. AC220V and DC24V versions cannot be interchanged.
16. Confirm operation mode requirements: H3BA-8 supports flashing and one-shot. Simplified models only for plain on-delay if flashing/one-shot not needed.
17. Contact rating: Max 5A for resistive loads. Add intermediate relay for inductive loads such as contactors or solenoid valves.
18. Risks for used procurement: Discontinued for decades, capacitor aging is inherent risk. Perform power-on burn-in test before acceptance.
19. HS Code Reference

85364900 (Time relay, electromagnetic / solid-state delay relay)

H3BA-8 Replacement Model List (sorted by recommendation priority)

Original H3BA-8: 8-pin round plug, 4 modes (A On-delay / B OFF-start flash / B2 ON-start flash / J one-shot), DPDT timed contacts, reusable base P3G-08/PF085A

✅ OMRON Original Preferred Replacements (direct plug into existing base, priority)

1. H3CR-A8【Official first choice, highly recommended】

Pinout fully compatible with H3BA-8, legacy P3G-08 base can be reused without rewiring

Functions: Full coverage of 4 basic modes (A/B/B2/J), time range 0.05s～300h, analog knob setting, DPDT timed contacts, AC250V 5A

Difference: Body approx.12mm shorter than H3BA-8. Panel mounting clip needs replacement with Y92H-8 (PF085A base) / Y92H-7 (PL08 base). Electrical wiring unaffected.

Application: Most equipment retrofits, original logic unchanged.

2. H3CR-A8E (version with instantaneous contacts)

Same pin compatibility with original base; adds one set of instantaneous contacts, matching capability of legacy H3BA-8H

Selection scenario: Choose A8E if circuit requires combined instantaneous + delayed output; not required for simple delay / flashing logic.

Contacts: Timed DPDT + instantaneous SPDT

3. H3BA-N8H (H3BA series upgraded successor)

Same H3BA second generation, 8-pin round base compatible; more modes (including mode A/H), time range 1.2s~300h

Feature: Switchable between【dual timed DPDT】or【timed SPDT + instantaneous SPDT】

Caution: Not fully equivalent to legacy H3BA-8. DIP switch logic differs. Requires mode re-calibration after replacement. Better for new projects. H3CR-A8 preferred for direct retrofit of old machines.

⚠️ OMRON Alternatives (simplified functions, not recommended for seamless direct swap)

H3Y-2-C: 8-pin, only simple on-delay, no flashing or one-shot. Only suitable for mode A (on-delay) applications, cannot run cyclic flashing. Function incomplete.

H3CR-A8S: Transistor output type, no relay contacts. Cannot directly replace contact circuits. Only for low-level PLC input signals, not for driving contactors or solenoid valves.

🇨🇳 Domestic Alternatives (cost saving, base compatible, verify pinout)

All 8-pin round socket (P3G-08), pin wiring same as OMRON, 4-mode multi-function timer

1. ST3PA-B (most common domestic model, 4 modes, 0.05s~300h, 5A contacts)
2. JSZ3A-B: Domestic 8-pin multi-function timer, specs benchmark H3CR-A8

Risk note: Domestic units have larger temperature drift and inferior long-term stability vs OMRON. Use caution for critical equipment.

Selection Comparison Table

Key Replacement Notes

1. Voltage must match: AC220V / AC110V / DC24V are not interchangeable, most common mistake.
2. DIP switch setting: H3CR-A8 DIP logic matches legacy H3BA-8. Always re-verify mode after replacement.
3. Contact rating: Max 5A resistive load. Add intermediate relay for inductive loads like contactors and solenoid valves.
4. Mounting clip: H3CR-A8 shorter body. Original panel retainer clip cannot be reused; Y92H series clips sold separately, no impact on electrical wiring.

OMRON H3BA Full Series Model List (Legacy Discontinued First Generation + H3BA-N Upgraded Generation)

Remark: First-generation H3BA (H3BA / H3BA-8 / H3BA-8H) discontinued in 1997. H3BA-N / H3BA-N8H are later upgraded versions of the same series, some stock still available. H3BA-X simplified single-delay variant also exists.

1. First-Generation H3BA (Legacy, discontinued; your H3BA-8 belongs to this group)

Voltage suffix breakdown: AC100/110V, AC200/220V, DC24V. Example: H3BA-8 AC220V, H3BA-8 DC24V.

2. Upgraded H3BA-N Series (H3BA second generation, same family)

Voltage suffix also AC110V / AC220V / DC24V.

3. Same Platform Derivative Series (H3B family, frequently compared during selection)

Same base footprint as H3BA-N, different functional positioning, not part of H3BA series, often quoted together for procurement

1. H3BF-N / H3BF-N8: Dual timer (two independent timing stages)
2. H3BG-N / H3BG-N8 / H3BG-N8H: Star-delta starter dedicated timer
3. H3BH-N / H3BH-N8: Off-delay timer
4. H3BA Series Model Coding Rules (Quick model decoding)

H3BA: Series code, multi-function analog solid-state timer

Numeric suffix: 8 = 8-pin round socket; no number = 11-pin round socket

Suffix H: Version with instantaneous contacts

Suffix S: Transistor output (no relay contacts)

Suffix N: Second-generation upgraded version (H3BA-N)

Suffix X: Simplified variant, on-delay only, no flashing or one-shot

HA/HB/HC: Time range differentiation for H3BA-X internal settings

5. H3BA Series Official Replacement Summary Table

6. Selection Remarks
7. Legacy H3BA / H3BA-8 fully discontinued, only surplus / used stock. Internal electrolytic capacitor aging is inherent failure mode.
8. H3BA-N8H uses same 8-pin base as H3BA-8, but DIP switch mode logic differs from legacy H3BA-8. Re-calibrate modes if directly replaced.
9. H3BA-X series cannot replace H3BA-8, missing B/B2/J flashing and one-shot modes; only simple on-delay available.