If you are using the fixed power system, the CRS has different power zones.
See http://www.cisco.com/c/en/us/td/docs/routers/crs/crs1/16_slot_lc/system_description/reference/guide/qsysdsc/sysdsc2.html#86923
For example, the CRS-16 below only has one linecard in zone 4 (slots 8-11) but three cards in zone 1(slots 0-3).
RP/0/RP0/CPU0:CRS(admin)#show environment power-supply
Power Module Voltage Current
AC-REC AC-REC (V) (A)
Rack 0:
Zone 1: [A0], [B0] 55.392, 55.623 7.233, 10.931
Zone 2: [A0], [B0] 55.623, 55.835 5.938, 6.185
Zone 3: [A1], [B1] 55.026, 55.430 0.924, 2.383
Zone 4: [A1], [B1] 55.797, 54.679 1.520, 1.561
Zone 5: [A2], [B2] 56.009, 55.122 6.781, 4.417
Zone 6: [A2], [B2] 55.103, 54.428 2.691, 2.116