7PG2113/4/5/6 Commissioning & Maintenance
©2012 Siemens Protection Devices Limited
Chapter 6 Page 23 of 77
directional boundaries in the opposite (lag) direction. The recorded angle should be the angle at which the
phase current leads the phase-phase polarising voltage. This measurement is greatly simplified if the
polarising reference voltage is set to 0deg and the current phase angle is measured with respect to this
reference.
Alternatively, the instrument can be checked at the 4 points marked a,b,c & d on Figure 2-1 only.
Forward Reverse
Lag (point C)
Lead (point A)
Lead(point B)
Lag (point D)
Pick-up Drop-off Pick-up Drop-off Pick-up Drop-off Pick-up Drop-off
MTA
MTA-85
MTA+85
MTA-85
MTA-85
Phase A
Phase B
Phase C
Table 2.2-3
Directional Limits Test Results
Figure 2.2-1 Directional Phase Fault Boundary System Angles
5. With the instrument reading ‘Fwd’ or ‘Rev’, reduce the voltage until the element resets. Record the minimum
phase-phase operate voltage.
Minimum Voltage Setting
Measured
Table 2.2-4
Minimum polarising Voltage Results