Siemens LOGO! 24RCE: Controlling Hayward HRCK2AK1 3-Way Valve

1. Application Overview

The marine utility system in this application requires a 3-way electric actuator valve (Hayward HRCK2AK1) to be sequenced on a recurring hourly basis:

• Filtered water port active for the first 10 minutes of every hour.
• Total (bypass) water port active for the remaining 50 minutes of the hour.
• Operation is 100% remote from the bridge/engine room — the valve's local/remote selector stays locked in REMOTE.

The control platform selected is the Siemens LOGO! 24RCE (6ED1052-1HB08-0BA8), a logic-module PLC with four relay outputs rated 10 A at 240 V AC. The valve actuator itself runs on 120 V AC, which is well within the relay contact rating. The control program is developed in LOGO!Soft Comfort V8.x (LSC V8) and downloaded to the LOGO! over Ethernet.

This article consolidates the wiring, voltage-spike observations, output mapping, and timer-block logic that the field installer needs to commission the cycle without damaging either the PLC or the actuator.

2. Prerequisites

3. Hayward HRCK2AK1 Valve Electrical Interface

The HRCK2AK1 is a 3-way ball/diverter valve with an integral electric actuator. The actuator carries a wiring terminal block on its cover that includes a power common, a "RUN CLOSED" command input, and a "RUN OPEN" command input. The local/remote selector routes either the on-board pushbuttons or the remote dry-contact inputs to those command terminals.

Refer to the Hayward commercial products documentation portal for the actuator nameplate data and the exact torque/current draw of the HRCK2AK1 motor before sizing the MCB.

4. LOGO! 24RCE (0BA8) Output Ratings

The 0BA8 generation LOGO! 24RCE provides four electromechanical relay outputs. The following ratings are from the Siemens LOGO! 0BA8 manual:

The 120 V AC / typically 0.5–1 A inductive motor load of the HRCK2AK1 sits well below the AC-15 derating curve, so contact life is dictated by switching frequency, not thermal capacity.

5. Wiring Topology: Relay Outputs to Valve Terminals

The MCB sits in series with the 120 V AC L1 conductor feeding the valve's "Common" terminal. The two dry-contact command lines route to Q1 and Q2 of the LOGO!. The valve's local/remote selector is left on REMOTE and the cover is locked, so the actuator only responds to PLC commands.

6. Voltage Spike & Snubber Considerations

A field measurement at the valve terminals shows approximately 200 V AC while the motor is in motion and 120 V AC once the valve reaches the end-stop. The 120 V steady-state value is simply the supply; the elevated mid-stroke reading is consistent with the unloaded back-EMF contribution of the series-wound AC motor as it decelerates. The leading edge of each direction-change command can therefore produce a transient that, while not destructive to the LOGO! 10 A contacts in itself, will accelerate contact wear and inject noise into the 24 V rail.

Recommended mitigations:

1. Install a 130–150 Vrms metal-oxide varistor (MOV) directly across the valve motor terminals inside the actuator cover.
2. Add a 0.1 µF X2-class capacitor in series with a 100 Ω ¼ W resistor across each LOGO! output contact (Q1 and Q2).
3. Keep the 120 V feeder separate from the 24 V DC sensor wiring by at least 100 mm in the cable tray.

7. Output Mapping: Q1 (RUN CLOSED) and Q2 (RUN OPEN)

The LOGO!'s relay outputs are single-pole normally-open (SPST-NO) dry contacts — there is no common terminal on the relay. The "common" of the run command is therefore the 120 V AC L1 conductor feeding the valve's common terminal. The two outputs simply switch L1 onto terminal 4 or terminal 6 of the valve:

Because Q1 and Q2 share the same L1 source, both command lines are at 120 V AC whenever the corresponding relay is closed. This is electrically identical to the way the previous ADU208 USB relay device was wired, with the LOGO!'s pin 1 acting as the "common" of each output.

8. Timer Logic Design (10 min on / 50 min off)

The cycle target is straightforward: at the start of every clock hour, energize Q2 (RUN OPEN / filtered) for 10 minutes, then de-energize Q2, pause briefly, then energize Q1 (RUN CLOSED / total) for the remaining 50 minutes. The cleanest implementation in LSC V8 is an Asynchronous Pulse Generator (B5) with adjustable on/off ratio, plus a short off-delay to give the valve time to reach its end-stop before the opposite direction is commanded.

Recommended block chain:

1. Hour pulse source — either the LOGO!'s built-in time-of-year clock, or a 1-hour clock generator (B1 → T = 1 h) so the cycle is decoupled from wall-clock time and is repeatable on power-up.
2. Pulse generator (B5) — on time = 10 min, off time = 50 min. Use this to drive Q2 directly. The pulse generator auto-retriggers on the rising edge of its trigger input.
3. Interlock pause (B4 — Off-Delay, 15 s) — placed between the B5 output and Q2. Also used to delay Q1's energization by the same amount so Q1 and Q2 are never closed simultaneously.
4. Inverse (B2 — NOT) — Q2 is inverted and fed through the same off-delay to drive Q1, so Q1 follows the 50-min portion of the cycle, also with the 15 s pause guard.
5. AND (B3) — final gating of Q1 with the off-delay output to enforce the pause.

9. Step-by-Step LSC V8 Programming

1. Open LSC V8 → File → New. Select the LOGO! 0BA8 device. Confirm the IP address matches the LOGO! on the ship's network and that the Ethernet cable is connected to the RJ45 port of the 24RCE.
2. Drop a Clock (B1) from the Special Functions toolbox. Set the period to 01:00:00 (1 hour). The Q output of B1 is a 1-second pulse every hour and acts as the cycle reset.
3. Drop an Asynchronous Pulse Generator (B5). Configure:
   • Trigger input: from the Q output of B1 (rising edge starts the cycle).
   • Pulse width TH: 00:10:00 (10 min on).
   • Pause width TL: 00:50:00 (50 min off).
4. Drop a Off-Delay (B4). Time: 00:00:15. The output of B4 drives Q2.
5. Insert a NOT (B2) at the B5 output to invert the 10-min signal into a 50-min active-low signal. Feed the inverted output into a second Off-Delay (B6), also set to 00:00:15, whose output drives Q1.
6. Add a final AND (B3) between B6's output and a permanent Hi constant to keep Q1 OFF during the first 10 minutes of every cycle. The B6 off-delay guarantees a 15-second gap between Q2 dropping and Q1 rising.
7. Map Q1 to the RUN CLOSED output and Q2 to the RUN OPEN output. Q3 and Q4 are spare — use them for an indicator lamp (cycle running) and an alarm (MCB trip via an auxiliary contact).
8. Press F5 (Simulation). Use the time-acceleration slider to verify that Q2 closes for 10 min, both outputs are open for 15 s, then Q1 closes for ~49 min 45 s, and that the cycle repeats automatically.
9. Press F4 (Download) → PC → LOGO!. Select Ethernet and confirm the device LED pattern switches to RUN.

10. Interlock Pause Time Between Direction Changes

Even with one output, the valve will physically require a few seconds to traverse from one seat to the other. The 15-second off-delay is therefore not just an electrical interlock — it is also a mechanical grace period. For the HRCK2AK1 the published stroke time is typically 6–10 s, so 15 s is conservative.

Mechanical interlock in software is implemented as:

Q1_enabled = B6_output AND NOT(Q2)
Q2_enabled = B4_output AND NOT(Q1)

This guarantees that Q1 and Q2 can never be closed at the same instant, eliminating the risk of driving the actuator motor against itself and burning out the windings.

11. Circuit Protection & Marine Considerations

• Install the 6 A MCB as close to the valve feeder as possible. Use a marine-listed breaker with a drip-proof enclosure.
• Bond the valve body to the ship's hull ground using a dedicated green/yellow conductor — do not rely on the conduit as the ground path.
• Use tinned-copper stranded wire for both control and power runs. Heat-shrink all splices.
• Provide strain reliefs at both the LOGO! output terminal block and the valve cover gland.
• Use a Class T fuse or DC-rated MCB on the 24 V supply feeding the LOGO! if the vessel's 24 V DC battery bus is unfused.
• Label the LOGO! outputs at the terminal block: Q1 = "VALVE RUN CLOSED", Q2 = "VALVE RUN OPEN".
• Lock the valve selector at REMOTE with a small bracket or a tamper-evident seal to prevent accidental local-mode operation while the bridge is unattended.

12. Commissioning & Verification

1. With the MCB open, perform a point-to-point continuity check from LOGO! Q1 pin 2 to valve terminal 4 and from Q2 pin 2 to valve terminal 6.
2. Verify there is no continuity between Q1 pin 2 and Q2 pin 2 (no cross-wiring).
3. Close the 24 V DC supply to the LOGO! and confirm the RUN LED is steady green.
4. In LSC V8 go online (Tools → Online Test, or F6). Watch Q1 and Q2 in the status view; with the cycle in its 50-min portion, Q1 should be ON and Q2 OFF.
5. Manually advance the cycle by toggling I1 (a momentary pushbutton wired to input 1) to inject a trigger into B1. Confirm the 10-min filtered phase begins, with Q2 ON.
6. After 10 min, confirm Q2 drops, both outputs are OFF for ~15 s, then Q1 rises.
7. Listen for the actuator; the gear noise should cease at each end-stop. If the motor buzzes continuously, abort and check for mechanical binding.
8. Measure the current drawn by the valve motor with a clamp meter during a direction change; it should be 2–4× the running current for less than 1 second, then drop to near zero.

13. Troubleshooting Matrix