SIMMS
SIMMS: Description
SIMMS (Solid Insulation Moisture Measurement System) is a small portable diagnostic system, which can be easily and quickly connected to the oil sampling points of any transformer. Then, SIMMS automatically tracks the desired system temperatures and water content in the oil, and can provide the first data snapshot already within 30 - 40 minutes.
In this way, SIMMS gives us the overall desired time-related profile - water content in oil
Cw = Cw (t)
and both temperatures
Tu = Tu (t),
Tb = Tb (t)
- upper / bottom transformer temperatures and TTS as the main (averaged) transformer temperature.
However, for an accurate diagnosis of the moisture contamination of the insulation system it is necessary to carry out the precise evaluation of the transformer equilibrium condition - the water movement between the oil and the paper during the measurement must be minimized or stopped.
Therefore, the first and basic question to be asked after the measurement is: are the adequate equilibrium conditions (relatively) constant temperature TTS and water content in oil Cw in the transformer reached or not.
This evaluation is made by a lap-top connected by cable to the SIMMS or from remote. The data can then be used in TRACONAL.
Attention
The SIMMS evaluation of the water content in the oil is strictly based on the reading of the humidity (diluted water) and temperature of the oil only (Vaisala sensor).
The diagnostics of wet transformers is therefore not balasted by an usual, highly misleading reading of water bonded in acids (representing a subsequent and inevitable error in the evaluation of the water content in cellulose insulants of aged transformers).
For more detailed explanation of this crucial phenomenon
See: The water problem of aged transformers.