Inverse Time Overcurrent. (51C) - Siemens Argus 7SR21 Technical Manual

7SR210 & 7SR220 Commissioning & Maintenance Guide
Figure 2.4-2 Cold Load Logic diagram
Ensure that the Cold load active is not raised. This can be reset by CB closed for more than the Cold Load Drop-
off Time or current less than the Reduced Current Level for greater than the Reduced Current Time. Check the
Cold Load Pick-up Delay by applying or simulating CB Open. Measure the time delay before Cold Load Active is
raised. Apply current above the Reduced Current Level if this functionality is Enabled before applying CB Closed.
Measure the time for Cold Load Active to reset.
2.4.1

Inverse Time Overcurrent. (51C)

It will be advantageous to map the function being tested to temporarily drive the relevant Pickup output in the
Pickup Config sub-menu in the Output Config menu as this will allow the Pick-up led to operate for the function.
Gradually increase current until Pickup LED operates.
Apply 2x setting current and record operating time.
Apply 5x setting current and record operating time.
Compare to calculated values for operating times
© 2013 Siemens Protection Devices Limited Page 23 of 82