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Compatibility testing: AmbiRad portable heaters utilising a generator.

Field Evaluation Report Compatibility testing: AmbiRad portable heaters utilising a generator to supply 230Vac.


The use of the Honda EU10i generator in supplying mains power to AmbiRad Portable units should cause no detectable change in either the unit’s performance or reliability. However, the use of the Kawasaki GA1400A should be avoided due to the high harmonic content of its output voltage.
The voltage regulation and stability of both generators was acceptable.

Note 1:
To ensure that the flame detector works correctly and to avoid any risk of electric shocks, it is also important that the “neutral” connection to the generator and the metal of the heating appliance are both connected to an effective earth conductor.

Note 2:
Note maximum rating of individual heater.

In supporting the use of this Honda generator, AmbiRad cannot take responsibility for any other compatibility issues which may arise due to some other components within the AmbiRad heater. However, it is also not easy to see what other issues could occur, providing the generator is not overloaded.

Summary of Results

When all measurements were normalised to a mains voltage of 230VAC, the Honda and Kawasaki generators were seen to cause an increase of 1.5% and 13%, respectively in the power dissipation in the zener diode, Z3 and an increase of 3% and 26%, respectively, in the power dissipation within resistor, R6.
All other components on the portable unit should not experience any change in dissipation levels, given the same RMS voltage range (230V +10%, -15%).
The voltage regulation over the load range from 10VA to 500W was found to be -2.2% for the Honda generator and +1.3% for the Kawasaki generator.


1. Ensure adequate earthing of the appliance for both safety and operational reasons,
2. Ensuring a sign-wave supply with minimum distortion and
3. Ensure voltage and frequency are both within limits.

Adequate Earthing
To avoid the risk of electrical shocks, it is invariably a safe practice to establish a reliable connection between the accessible metal parts of the appliance and a local earth connection, be it a cable connection to an existing earthing point or, failing this, to establish your own effective earth, locally*. We also recommend that the earth connecting cable to the appliance should be rated at least 5 times higher than the fuse protecting the appliance.
Having made this connection, we then recommend that the output supply connection, labelled "Neutral", is also connected to the same earth via a 2Mohm resistor rated for operation at 1500VAC. This will then ensure that the flame detector works reliably, while not compromising any flash testing requirements.
For extra security, it is also recommended that a residual current circuit breaker (RCCB) is fitted between the generator output and the appliance, "downstream" of the above earth connection.

Adequate purity of Waveform
Automatic electronic controllers used in AmbiRad portable heaters require to work from a power supply with a relatively pure sine waveform (say, less than 5% harmonic content). Most professional grade generators will provide this, but the question should still be asked.
If the harmonic distortion exceeds, say, 10% there is an increasing risk of early failure of our internal power supply and so failure of the appliance.

Correct Frequency and voltage ranges
Finally, the frequency of the waveform should be verified to be within +/-2.5Hz of 50 Hz, and the supply voltage within +10% and -15% of 230VAC. The operation of our controls are not specified outside these limits.

* Note : Where no convenient earthing facility exists and you need to establish your own, please make reference to THE ELECTRICITY AT WORK REGULATIONS 1989 and the IEE Wiring Regulations.

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Last Modified on 02/11/2007.
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