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50-LP-AC10 LatchPac solid state relay
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50-LP-AC10 — LatchPac Solid State Latching Relay — 1-Pack

Latching solid state AC relay, 24–240 VAC, 10 A, 40 A inrush

SKU 50-LP-AC10 · 1-Pack
1-Pack5-Pack
Coming Soon

The 50-LP-AC10 LatchPac is in development and pricing has not yet been determined. Contact us for availability and pre-order information.

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Specifications
Switching modeDP latching
Voltage range24 – 240 VAC, 50–60 Hz
Maximum load10 A
Maximum inrush40 A
Maximum surge15 A
Sensor circuit resistance1000 ohms max
Input sense voltage5 VDC
Dissipation32 watts per amp switched
Heat sink required above0.75 A
Base isolation1000 VDC
Dimensions2.43″ × 1.600″ × 0.97″ (61.72 × 40.64 × 24.57 mm)
Ambient temperature0 – 140 °F at 100% duty cycle
TerminalsEurostyle® screw type
ComplianceRoHS compliant

Product Description

The 50-LP-AC10 LatchPac is a solid state latching relay built for wide-differential level control. Where the NistorPac follows its sensor directly, the LatchPac latches: it stays on after the starting sensor releases, and stays on until a second sensor unlatches it. That is what makes pump-down and pump-up control possible from two ERECTA SWITCH sensors — without a PLC or a logic controller.

How the latch works

Load connects to terminals E and F and line voltage to G and H, leaving the relay in standby, poised to switch. The start switch connects to terminals A and B; the stop switch to C and D. Control is accomplished when both switches are closed — the circuit turns on and stays on until both switches are open. For Start Low / Stop High, configure both sensors to open on rise; for Start High / Stop Low, configure both to close on rise.

The result is a wide differential between the start and stop levels, which is what eliminates the short-cycling and contact chatter you get when a single sensor sits near its trip point. Because the latch holds, brief signal disruptions and sensor bounce do not interrupt the load.

Wiring and heat

Eurostyle® screw terminal blocks accept two wires from the voltage source, two from the load, two from the start sensor and two from the stop sensor; optional ferrules simplify the terminal blocks. Use AWG 20 minimum for sensor circuits and AWG 18 minimum for line and load. A heat sink is required above 0.75 A continuous. The relay carries 1000 VDC base isolation between the sensor circuit and the load, and operates at 100% duty cycle across 0–140 °F.

Where it is used

Sump pump control from high and low level sensors, tank fill and drain sequencing, overflow protection in rinse stations and chemical tanks, backup pump control in flood response systems, dual-float logic for IBC totes and storage tanks, and valve sequencing in fluid processing. Any application with long cycle times or widely spaced setpoints benefits from the latch. It accepts any passive SPST switch meeting the 5 VDC input sense and 1000 ohm maximum sensor resistance — including Series 10 and Series 20 float switches.

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Frequently Asked Questions

Common Questions About This Product

What does the 50-LP-AC10 do, and why would I need one?

It is a solid state AC switching relay for OEM equipment. A reed or float sensor gives a reliable, low-power contact closure but cannot directly drive a pump motor, solenoid or other high-current load. The 50-LP-AC10 bridges that gap: the sensor pilots the relay, and the relay switches the load — letting a sensor handle a bigger job than it could by itself.

What can I use to control the 50-LP-AC10?

Any dry contact or passive SPST sensor will pilot it — reed switches, float switches, bimetallic temperature switches, flow switches, magnetic contacts, thermostats and pressure switches. That makes it useful well beyond liquid level: thermal shutdown interlocks, HVAC damper and blower control, and light-duty feeders or mixers driven from a simple contact closure.

What load can the 50-LP-AC10 switch?

Series 50 relays switch line-voltage AC loads, and the exact voltage range, continuous load rating, maximum surge and minimum load are listed in the specification table on this page — they differ between models, so read the table for the one you are specifying rather than assuming. Note there is a MINIMUM load as well as a maximum: below it the relay may not switch cleanly.

How do I wire the 50-LP-AC10?

Eurostyle® screw terminals take three pairs: line voltage, the load device, and the sensor. The load connects to terminals A and F, line voltage to B and E, and the sensor to C and D. Control is simply completing and interrupting the sensor circuit — the load stays on for exactly as long as that circuit is complete. Observe polarity conventions for your line and load circuits and fuse both to the applicable equipment codes.

Does the 50-LP-AC10 need a heat sink?

It depends on the current you are switching, and the threshold is on the specification table on this page. The relay dissipates heat only while the load is on. Below the stated threshold the built-in heat sink is sufficient; above it, the relay must be attached to a supplemental heat sink or any cool metal surface of adequate area to keep it from overheating.

What are the advantages over a mechanical relay?

It has no moving parts, so it is silent, cannot suffer contact wear, and does not arc. That matters in OEM equipment expected to cycle for years without service, and in enclosures where arcing contacts are undesirable. ⚠ Note it is a solid state device: it passes a small leakage current through the load terminal even when off, which the specification table quantifies — check that your load tolerates it.