28 Jan 2021 : Hioki AC Leakage Clamp Meter CM4003 For Troubleshooting Intermittent RCD Tripping

Hioki AC Leakage Clamp Meter CM4003 for Troubleshooting Intermittent RCD Tripping

What is RCD? 

Residual Current Device (RCD) is a generic term for safety devices that switch off electricity automatically if there’s any fault [1]. It protects against accidental electrocution to users, equipment malfunctions, and fire hazards to properties. RCD monitors the Residual Current level (the current difference between the live wire and the neutral wire) versus its rated nominal tripping current to disconnect the power supply [2]. Residual Current is due to leakage current from old or damaged insulation of equipment flowing to the ground through a conductive path. Some example of RCDs are as follow:

Figure 1.0 Examples of Residual Current Devices (RCDs)

1. Residual Current Circuit Breaker (RCCB)
2. Residual Current Circuit Breaker with overload protection (RCBO)
3. Earth Fault Relay (EFR)
4. Earth Leakage Relay (ELR)

Leakage Current Measurement and Intermittent RCD Tripping 

RCD will trip whenever a leakage current exceeds the designated RCD’s threshold value. A high leakage current can cause unnecessary and intermittent RCD tripping. Therefore, leakage current measurement can help detect potential issues in the circuits and prevent problems such as intermittent RCD tripping. This measurement can also help trace the source of leakage current.

A leakage current sensor clamp is clamped to the round-trip wiring or ground conductors for leakage current measurement, as shown in Figure 2.0 below.

Figure 2.0 Leakage Current measurement method

1. Single Phase Circuits (phase and neutral conductors)
2. Three-phase Circuits (all 3 phases and neutral conductors)
3. Ground Circuit (for total leakage checking)

 

The source of leakage current tracing starts from the conductor line to the main panel (upstream) right down to individual circuits (downstream) until it is found (Figure 3.0).

Figure 3.0 Leakage Current Source Tracing Methodology (Upstream to Downstream)

 

Hioki AC Leakage Clamp Meter CM4003 Troubleshooting
Intermittent RCD Tripping

Intermittent RCD tripping is unpredictable and time-consuming to troubleshoot in normal circumstances. Hioki’s CM4003 is capable of measuring leakage current values and recording intermittent tripping events of RCDs. The threshold value of leakage current values for an event recording trigger is configurable by users. Below are the steps of using CM4003 as a troubleshooting tool for intermittent tripping:

1. Install a Clamp Meter on each circuit
2. Set the recording conditions using the tablet (threshold value *2 and recording time) and start event recording

*2: Level of leakage current you wish to detect

*3 Recording Time: Up to 30 days (Battery operation is limited by the life of the batteries. Only the CM4003 can be powered by an external power supply)

Number of recorded events: Up to 999 (CM4002/CM4003; CM4001: 99)

Import data using GENNECT Cross

1. Trip event recorded with leakage value and time of event

For a long duration of continuous measurement recording, CM4003 can be paired with the AC adaptor Z1013 for external power supply and Hioki’s Memory HiCorder for output function, as illustrated in Figure 4.0 below.

 

Convenient Functionality exclusive to the CM4003

Figure 4.0 CM4003 set-up for long duration of continuous measurement recording (RCDs)

Output function (waveform/RMS): Use a recorder to record waveforms and fluctuations
External Power Supply: Use an AC Adapter*3 for continuous, long-term measurement

 

Key Features of the CM4003

 

1. Minimum resolution of 0.01mA

- Range: 6.000mA - 200.0A
- Comply with IE61557-13

2. Uniform measurement sensitivity regardless of conductor position inside the jaws

3. Large jaw size for single thick wire or multiple wires

4. Bluetooth option with Wireless Adapter Z3210 (Optional) to connect with GENNECT Cross software (Tablet / Mobile)

5. AC Adapter (Optional) for long duration of leakage current data logging (up to 999 events on standalone mode)

6. Resistance to external magnetic field

7. Able to measure AC inrush current (measured value will be auto-hold)

8. Comparator function with warning sound and warning red backlight if measured values exceeds threshold value

 

Alternatives for Leakage Current Measurements

The following Hioki Portable Power Meters are alternatives to CM4003 for leakage current measurement:

 

i. Power Logger PW3360 + Clamp On Leak Sensor 9657-10
ii. Power Logger PW3365 + Clamp On Leak Sensor 9657-10
iii. Power Quality Analyzer PQ3100 + AC Leakage Sensor CT7116
iv. Power Quality Analyzer PQ3198 + AC Leakage Sensor CT7116

For more information on Hioki AC Leakage Clamp Meter CM4003, please click the link here:  Hioki AC Leakage Clamp Meter CM4003

Download Product Catalog

References

1. https://www.electricalsafetyfirst.org.uk/guidance/safety-around-the-home/rcds-explained/

2. https://electrical.theiet.org/wiring-matters/years/2019/77-september-2019/which-rcd-type/#:~:text=Whilst%20RCDs%20have%20a%20nominal,18%20mA%20to%2028%20mA.