Tech Forum

Q: Can NRG specify by serial number which sensors can enter the vibratory mode? How do we determine if sensors delivered are within the problem batch(es)?

A:  #40C anemometers with serial numbers 26130 - 92049 are potentially affected. This is not a batch issue. It is a function of the individual sensor and its susceptibility to entering a vibratory mode.

Do you mean that serial no like 179500038313 could be affected by the vibratory mode problem? or do i have to remove some digits from this number in which case, which one will be the serial number for this anemometer?

The range listed above corresponds to the last 5 digits of the #40C's serial number.

 e.g. 179500038313 would be 38313.

Data from four #40C anemometers on a mast installed in 2007 suggests that we may be seeing evidence of this failure mode. The serial numbers recorded by the field crew who installed the mast at first suggest that the senors are pre-2006 and so should not be affected (Sn: 2820, 2803, 2798 & 23912). But from your response it would appear that they could well be affected as the leading digits may not have been recorded.  However, I then looked at some sensors we currently have in store and the serial numbers on these do not fit the convention you describe, examples being:

• one is hand scribed with the serial number: otc17174,
• another is hand scribed with the serial number: 6567-16,
• and another has no serial number on it at all.

What is the reason behind the use of the above concention for identifying sensors and how do I relate this to year of manufacture?

Hi -

It appears that the sensors you have are older than the potentially affected group. 

• OTC17174 was produced in 2004.
• The sensor without a serial number on it may have a date code label at the sensor base which specifies the sensor age.  If the sensor does not have this label, it is also older than the potentially affected group.
• The sensors 2820, 2803 and 2798 are also likely to be older NRG sensors which are not potentially affected but it would be good to check for the label at the sensor base.
• 6567-16 is not an NRG serial number format.  Check for the datecode label.