Omron H3DT-HBL 24-48 VAC/VDC — Power OFF-Delay Timer 1-120 s
SKU: H3DT-HBL AC-DC24-48VUSD 41.00
22.5 mm DIN-rail power-OFF-delay timer with SPDT 5 A output; supply 24-48 VAC/VDC; two time ranges 1-12 s and 10-120 s. Holds the relay energized for the set delay after power is removed — for 'coast-down' or 'fail-safe delay' timing.
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Product Overview
The H3DT-HBL 24-48 VAC/VDC is Omron's 22.5 mm-wide power OFF-delay timer — a special-purpose timing relay where the SPDT contact stays energized for a configurable time after the supply voltage is removed. This is the inverse of the standard ON-delay timer (H3DS-ML, already in catalog) which holds the relay OFF for a set time after power comes ON.
Decoding the H3DT-HBL model number
H3DT = H3DT-series DIN-rail timer (the successor to the older H3DR / H3DS series, with improved EMC immunity). H = Hold / Power OFF-delay operation mode (vs S = ON-delay, F = flicker, R = repeat cycle in the broader H3DT family). B = Body 22.5 mm wide (the larger 17.5 mm H3DT-SL is the alternate slim variant). L = Latching form-C (SPDT, single Form C contact — vs 2L = DPDT, 2× Form C; L vs 2L naming comes from the legacy H3CA series). The actual SKU on the housing reads 'H3DT-HBL' — three letters pack the function, form factor, and contact type.
Power OFF-delay operation principle
When the supply voltage is applied: the SPDT contact closes immediately (instantaneous operation) and the internal timing capacitor charges. When the supply is removed: the SPDT contact stays closed for the set period (1-12 s or 10-120 s, depending on dial position), then opens. The 'minimum power-ON time' is 0.3 s — the supply must be present for at least 300 ms before being removed, otherwise the timing capacitor isn't fully charged and the OFF-delay time will be shorter than the dial setting.
Time ranges — dual-range dial
The H3DT-HBL has two time ranges selected by a continuous analog dial: '1-12 s' (low range, 1-12 second delay) and '10-120 s' (high range, 10-120 second delay). The high range covers most coast-down applications (1-2 minutes is typical for fan or pump coast-down). The low range is useful for nuisance-power-dip ride-through (5-10 seconds of contact hold-up during a 1-second power dip — keeps the relay contact closed during a typical contactor drop-out event). The dial is a 0-100% fraction of the selected range (so 50% on the 10-120 s scale = 60 seconds).
Key Features
- H3DT-series DIN-rail power OFF-delay timer
- Power OFF-delay mode
- 22.5 mm wide
- SPDT output contact, single Form C
- Coil/supply voltage 24-48 VAC/VDC universal
- Time range 1-12 seconds and 10-120 seconds, selected by dial
- Continuous analog time-setting dial
- Time accuracy ±1% of full scale maximum
- SKU: H3DT-HBL AC-DC24-48V
- Series: H3DT Power OFF-Delay Timers
- Voltage: 24 TO 48 VAC
- I/O: 1 I/O
Best-Fit Applications
- Cooling-fan coast-down for a plastics-extrusion heater — the heater's 230 VAC control contactor is wired through the H3DT-HBL's SPDT: when.
- Lubrication-pump run-on after machine stop — when an industrial press's run-permission signal is removed, the H3DT-HBL holds the lubrication-pump contactor.
- Power-dip ride-through on a control panel — when a brief utility brownout or fault clears within seconds, the H3DT-HBL holds.
- Door-interlock delay after emergency stop — when the E-stop button is hit, the H3DT-HBL keeps the safety-door relay engaged for.
Buying Checklist
- Pick H3DT-HBL 24-48 VAC/VDC for 22.5 mm SPDT power OFF-delay timer with 1-12 / 10-120 s dual range
- Pick H3DS-ML AC-DC24-48 / DC24-230 for 17.5 mm universal multi-function 8-mode timer with 0.1 s-120 h range
- Pick H3DT-SL for slim 17.5 mm **ON-delay** function in the H3DT family
- Pick H3DT-FL for flicker / repeat-cycle timing
- Pick H3DK-M2 AC-DC24-240V for 8-mode timer with 24-240 VAC/VDC universal supply
- Pick H3YN-2-B DC24V for plug-in 4-mode timer with octal-pin socket for removable installation
Technical Specifications
| Model | H3DT-HBL AC/DC24-48V |
|---|---|
| Series | H3DT Power OFF-Delay Timers |
| Type | Power OFF-delay timer, 22.5 mm DIN-rail mount, SPDT output |
| Operating Mode | Power OFF-delay (relay stays energized for set time after supply is removed) |
| Operating / Resetting | Instantaneous operation / Time-limit reset (standard) |
| Number of Time Ranges | 2 (1-12 s and 10-120 s, continuous analog dial) |
| Time Range Low | 1 to 12 s |
| Time Range High | 10 to 120 s |
| Rated Supply Voltage | 24 to 48 VAC 50/60 Hz / 24 to 48 VDC |
| Operating Voltage Range | 20 to 53 VAC / 20 to 53 VDC |
| Output Configuration | SPDT (1 Form C, 3 terminals: COM-NO-NC) |
| Min Switching Capacity | 100 mA at 5 VDC |
| Output Indicator | Orange LED (lights when SPDT contact is closed) |
| Operating Temperature | -20 to +60 °C |
| Storage Temperature | -30 to +70 °C |
Resources & Downloads
FAQ for H3DT-HBL AC-DC24-48V
What is the difference between H3DT-HBL and H3DT-SL?
Both are H3DT-series DIN-rail timers in the same physical form factor (22.5 mm wide), but they differ in operating function: H3DT-HBL (this SKU) is a power OFF-delay timer — the SPDT contact closes immediately on power-on, then opens for the set time after power is removed. H3DT-SL is an ON-delay timer — the SPDT contact stays open for the set time after power-on, then closes indefinitely until power is removed (resets).
How do I set the time range on the H3DT-HBL?
The H3DT-HBL has a continuous analog dial on the front face with two numbers — a small 'low range' (1-12 s) and a large 'high range' (10-120 s). A selector pointer next to the dial chooses which range is active.
What happens if the supply voltage dips briefly (e.g., 200 ms brownout)?
Brief supply dips are the entire purpose of the H3DT-HBL's OFF-delay function. The internal timing capacitor holds enough energy to keep the SPDT contact closed during a 200 ms dip without resetting (typical). For a 1-second dip, the SPDT contact stays closed for the full duration of the dip and continues until the dip ends — the timer does NOT start timing during the dip; it just keeps the contact closed.
Can the H3DT-HBL drive a 230 VAC motor contactor coil?
Yes — the SPDT contact rating is 5 A at 250 VAC resistive (and 2 A at 250 VAC inductive with cosφ = 0.4), sufficient for direct switching of motor-contactor coils up to about 200 VA. Most industrial contactor coils (Schneider LC1D, Siemens 3RT, ABB AF, Eaton DIL) draw <10 VA at 230 VAC inrush and 5-8 VA held.
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