Oltc Motor Drive Current - Raytech mini-ATOS Instruction Manual

4.7 OLTC Motor Drive Current

Many mechanical and control problems of OLTC can be detected by the drive motor current. The
mini-ATOS can measure this current by utilizing a current clamp. This test can be performed
simultaneously with DRM. The measured current then would be shown as graph like Figure 7 for
comparing and the parameters according to Table 4 will be calculated.
Table 4: OLTC drive motor current parameters
Parameter Unit Description
Inrush [A] Initial inrush current peak for each tap transition
Tmotor [s] Duration of each tap transition
[Acyc] or Motor Current Index (IEEE C57.143-2012): The area under the motor
MCI
[Asec] current curve during whole tap transition
Figure 7: Typical motor current curve of a OLTC motor
Preliminary
90297-0.24 Instruction Manual mini-ATOS Page 24 of 125