CKD 4G4R (4GA4R/4GB4R) Solenoid Valves: Wiring & Installation

1. Technical Overview of the CKD 4G4R Series Power Saving Architecture

The CKD 4G4R Series represents a specialized evolution of the standard 4G pilot operated 5-port solenoid valves, specifically engineered for extreme energy efficiency. In modern industrial automation, reducing the heat signature within control cabinets and minimizing power consumption are critical objectives. The 4G4R series achieves this through a power-saving circuit (Option “E”) that reduces the holding wattage to 0.1W. This guide focuses on the technical nuances of installing and wiring these high-efficiency components, specifically focusing on the 4GA4R and 4GB4R variants.

The core technology behind the 4G4R series involves an integrated circuit within the coil assembly that manages the transition from an initial high-current inrush to a low-current holding state. When the PLC sends a signal to the valve, the coil receives a momentary burst of energy to move the armature, followed by a drastic reduction in current to maintain the position. This operation requires precise wiring and a stable power environment to ensure the internal power-saving circuit functions correctly without causing oscillation or premature failure of the electronic components.

2. Electrical Specifications and PLC Output Integration

Integrating the CKD 4G4R series into a control system requires a detailed understanding of the electrical characteristics of the 0.1W coil. Unlike standard solenoid valves that may pull 1.8W to 2W continuously, the 4G4R series presents a unique load profile to the PLC output module.

Table 1 Electrical Performance Data for 4G4R Series

A critical consideration for electrical engineers is the leakage current of the PLC output module. Because the 4G4R valve only requires 5mA to maintain its ON state, a PLC transistor output with a high leakage current might prevent the valve from switching OFF. In such cases, the residual current is sufficient to keep the power-saving circuit energized, leading to a stuck valve scenario. During field testing with a CKD 4GA410R-10-E2-3 model, it was observed that using an output module with a leakage current of 0.8mA provided a safe margin, whereas a module with 1.8mA leakage resulted in inconsistent de-energization.

3. Step-by-Step Individual Wiring and E-Connector Assembly

The CKD 4G4R series typically utilizes the E-connector system, which is a small, high-density plug-in connector designed to simplify field maintenance. Proper assembly of these connectors is vital to maintain the IP65 rating and ensure long-term electrical contact stability.

• Preparation of the Cable: Use a 2-core shielded cable for individual wiring. Strip the outer jacket by 20mm and the individual wire insulation by 3mm. Avoid over-stripping, as exposed copper can lead to short circuits within the cramped E-connector housing.
• Terminal Crimping: Use the designated CKD crimping tool to attach the socket terminals to the wires. Ensure the insulation support of the terminal firmly grips the wire insulation to provide strain relief.
• Housing Insertion: Insert the crimped terminals into the E-connector housing until a distinct click is heard. For a standard 4GA410R-10-E2-3 single solenoid valve, the polarities are usually assigned as Pin 1 for Positive (24V) and Pin 2 for Negative (0V).
• Orientation Check: The 4G4R series allows for the connector orientation to be changed. You can rotate the connector in 90-degree increments. When adjusting the orientation, ensure the internal gasket is not pinched, as this is a frequent cause of moisture ingress leading to circuit corrosion.

In a recent installation involving a 4GB420R-15-E2-FL-3 double solenoid valve, technicians reported a failure where the valve would chatter. Upon inspection, it was found that the crimping was performed with a generic tool, leading to high contact resistance. Replacing the terminals with correctly crimped CKD sockets resolved the voltage drop issue that was interfering with the internal power-saving IC.

4. Surge Suppression and Polarity Management

The 4G4R series supports a surge killer (optional) and an indicator lamp (optional). Additionally, the power-saving circuit (Option “E”) is offered with the indicator lamp only. However, the presence of the internal power-saving circuit makes the valve strictly polarity-dependent. Reversing the positive and negative leads will not only prevent the LED from lighting up but can also damage the internal IC if the reverse voltage exceeds the protection threshold for an extended period.

When wiring a manifold system, such as a 4GD4R1-08-E2N-3 block, always verify the common terminal configuration. If the manifold is configured for a Plus Common (NPN), all valves must share a common positive line. If Minus Common (PNP) is used, they share the negative line.

A field-proven checklist for wiring verification includes:Measuring the voltage at the connector pins under load to ensure it remains above 21.6V DC.Checking for surge voltage spikes using an oscilloscope on the DC line. While the 4G4R has internal protection, high-frequency noise from nearby VFDs can still bypass simple suppressors.Confirming the LED illuminates brightly. A dim LED often indicates a partial short or a voltage drop caused by undersized wiring over long distances.

5. Mechanical Installation and Manifold Mounting Best Practices

Beyond the electrical wiring, the mechanical mounting of the 4G4R series directly impacts the longevity of the seals and the efficiency of the pneumatic circuit. The 4G4R series features a compact design, but this means heat dissipation must be considered if multiple valves are mounted on a single manifold and energized simultaneously for long durations.

The mounting surface must be flat within 0.1mm. If the manifold is bolted to a warped machine frame, the valve body can experience torsional stress. This stress often leads to the spool sticking or the pilot valve becoming misaligned. When installing a 4GD4R1-08-E2N-3 manifold, technicians should use a torque wrench to tighten the mounting bolts to the specified 0.6 Nm to 1.0 Nm range. Over-tightening can deform the aluminum manifold base, while under-tightening leads to air leaks at the interface gasket.

One common failure observed in the field is the ingestion of debris during the initial installation of the piping. It is highly recommended to flush all pneumatic lines with compressed air before connecting them to the 4G4R valve ports. Even a small fragment of PTFE tape or a metal shard from a threaded pipe can obstruct the pilot orifice, which is particularly sensitive in the 4G4R series due to the low-force pilot requirements.

6. Advanced Troubleshooting of Low-Wattage Signal Oscillations

The 0.1W technology introduces a specific troubleshooting challenge: signal oscillation. This occurs when the power supply or the PLC output is unable to provide the initial inrush current of 1.8W, causing the valve to rapidly cycle between the starting and holding states. This chattering can be heard as a high-frequency buzzing and will eventually burn out the internal IC.

To diagnose this, engineers should measure the current profile during the first 100ms of activation. If the current does not reach the required 75mA for the full 50ms starting duration, the valve may not fully shift.

Checklist for Resolving Chattering Issues:Verify that the power supply has sufficient peak current capacity, especially if 10 or more valves are energized at the exact same millisecond.Check for Ghost Voltages on the line. In long cable runs, inductive coupling from AC power lines can induce enough voltage to confuse the low-power sensing circuit of the 4G4R.Inspect the E-connector for moisture. Even slight humidity can create a high-resistance path between pins, which at 4.2mA holding current, can significantly alter the circuit's behavior.

7. Comparative Analysis of Energy-Saving Circuit Topologies

To understand the superior reliability of the CKD 4G4R series, it is helpful to compare its internal circuitry with other common energy-saving methods used in the industry. Most low-power solenoid valves use one of two methods: the PWM Pulse Width Modulation method or the Dual-Coil transition method.

The 4G4R series utilizes an advanced integrated PWM control circuit within the solenoid head. In this architecture, the valve initially receives the full 24V DC to ensure a clean break-away of the spool from its static position. After a predefined interval of approximately 50ms, the internal IC begins high-frequency switching to lower the effective voltage. This is fundamentally different from a simple resistor-based voltage drop, which generates significant heat.

Field engineers often compare the 4G4R with competitor models that use a mechanical dual-coil system. In a dual-coil system, one high-power coil handles the inrush, and a second low-power coil handles the holding. However, the mechanical switching between these two coils can create inductive spikes that shorten the life of the PLC relay or transistor. The CKD 4G4R electronic transition is much smoother, as evidenced by the lack of high-frequency ripple when measured on a high-speed oscilloscope.

8. Integration with Fieldbus Communication and Manifold Blocks

For large-scale installations, the 4G4R series is often integrated into manifold blocks controlled via Fieldbus protocols such as EtherCAT or PROFINET. This requires a transition from individual wiring to a serial transmission slave unit.

When configuring a manifold like the 4GD4R series with a serial slave, the technical focus shifts from crimping wires to addressing and power distribution. A common mistake in manifold assembly is the improper isolation of the valve power supply from the logic power supply. The 4G4R series, while low power, still requires a clean 24V DC source for the valves that is separate from the sensitive communication electronics of the slave unit.

During a recent deployment of an 8-station EtherCAT manifold using 4G4R valves, an issue arose where the communication would drop whenever multiple valves were de-energized simultaneously. The investigation revealed that the back-EMF produced by the collapsing magnetic fields of the solenoid coils was interfering with the EtherCAT data packets. Even though the 4G4R has internal surge suppression, adding a 0.1 microfarad capacitor across the 24V and 0V power terminals of the manifold base significantly improved signal integrity.

9. Calculating Response Time and Pneumatic Efficiency

One common concern when switching to a reduced-wattage valve like the 4G4R is whether the response time is sacrificed for energy efficiency. Technically, the response time of a solenoid valve is the sum of the electrical delay and the mechanical delay.

Pneumatic Response Observation Table

In high-speed sorting applications, these 4-6 millisecond differences must be accounted for in the PLC timing logic. For example, if a sensor triggers a reject cylinder, the output pulse must be sent 5ms earlier when using the 4G4R compared to the standard 4G version. Failing to adjust this can lead to the cylinder missing the target at high conveyor speeds.

10. Environmental Adaptability and Chemical Resistance

In the food processing and chemical industries, the 4G4R series is often installed in environments where it may be exposed to cleaning agents or high humidity. The exterior of the 4G4R series is constructed from high-grade polybutylene terephthalate PBT and aluminum.

While the PBT housing offers excellent resistance to many industrial chemicals, certain esters and ketones can cause stress cracking over time. During installation, it is crucial to ensure that any thread sealants used on the NPT or G-thread ports do not contain chemicals that can degrade the plastic housing.

Technicians should also pay close attention to the pilot exhaust port. In the 4G4R series, the pilot exhaust is often vented locally. In dusty environments, this port can become partially blocked, leading to sluggish valve performance. Installing a small sintered bronze silencer on the pilot exhaust port can prevent dust ingress while maintaining the valve response characteristics.

11. Detailed Failure Mode Analysis and Preventive Maintenance

To ensure a 10-year service life, which is standard for CKD components in well-maintained systems, a preventive maintenance schedule must be established based on the specific failure modes of low-wattage electronics.

Failure Mode: Partial Spool ShiftCause: Inadequate inrush current from an overloaded 24V DC power supply.Symptom: Air leaks through the exhaust port while the valve is energized.Action: Upgrade the power supply or add a local buffer capacitor.

Failure Mode: Coil OverheatingCause: Continuous operation at voltages exceeding 26.4V DC.Symptom: Discoloration of the PBT housing and a smell of burnt plastic.Action: Install a voltage regulator to ensure a steady 24V DC.

Failure Mode: Delayed De-activationCause: High leakage current from PLC transistor output or inductive coupling.Symptom: Valve remains ON for 100-500ms after the PLC output turns OFF.Action: Install a bleeder resistor in parallel with the coil to drain the residual current.

12. Optimized PLC Programming for Reduced Wattage Valves

When programming for the CKD 4G4R series, certain software-level adjustments can enhance the system overall reliability. In platforms like GX Works3 for Mitsubishi or TIA Portal for Siemens, the output refresh rate and PWM settings should be checked.

Although the valve has an internal PWM circuit, the PLC should send a continuous 24V signal. Some advanced PLC modules have their own PWM functions for energy saving; these should be disabled for the outputs connected to the 4G4R series. If the PLC tries to PWM a valve that already has an internal PWM IC, the two frequencies will interfere, causing the internal IC to reset repeatedly.

Furthermore, implementing a Soft-Start logic is not necessary and can actually be detrimental. The 4G4R requires a sharp rising edge of the voltage to trigger the 50ms inrush timer. A slow voltage ramp will result in the valve attempting to hold before it has ever fully shifted.

13. Final Installation Checklist and Commissioning

Before the final handover of a machine utilizing the CKD 4G4R series, the following commissioning steps should be performed:Static Pressure Test: Pressurize the system to 0.7 MPa and use a leak detection spray on all manifold joints.Minimum Operating Pressure Check: Lower the system pressure to 0.2 MPa and ensure the valve still shifts reliably.Grounding Verification: Ensure the manifold base is properly grounded to the machine frame.Thermal Scan: After 1 hour of continuous cycling, use an infrared thermometer to check the coil temperature.

The CKD 4G4R series offers an unparalleled blend of efficiency and performance. By following these detailed wiring and installation protocols, technical teams can ensure that their automation systems are not only energy-efficient but also exceptionally reliable in the most demanding industrial environments.

Note to Readers: The technical information provided in this article is for educational purposes only and may vary based on specific site conditions and equipment revisions. Always consult the official manufacturer manuals and safety guidelines before performing electrical or pneumatic installation and maintenance.

The author assumes no liability for any loss, damage, or malfunction resulting from the use or application of this information. Use is strictly at the reader's own risk.

References

• CKD New Products: Pilot Operated 5-Port Solenoid Valves (M)4GA/B4R Series (Catalog No. CC-1657) (PDF)
• CKD 4G Series Common Technical Data / Usage Precautions (Technical Data) (PDF)