We are in need of Magnet for 30 Mt DG goliath crane. Single Hook crane Class -II medium duty

Span-20 Mtr Clear
HOL- 6 Mtr (Considering 5 Mtr below magnet )
LT-145 mtr

Speed of Equipment is as below.
MH: 6 M/min
CT: 20 M/min
LT: 30 M/min

04 nos of Magnet for Plate Lifting with Evener Beam Control from Remote for Magnet Control

Max. Length of Plate - 12 Mtrs
2. Max. Weight of Plate - 25 MT
Need Battery Back-up for Magnet & Hoist for any power Failure related issue.
4. Magnet position required to be interchangeable at every 01 Meter


Plate specification & other details is as below.

Length of Plates will be vary from 6 Mtr to 12 Mtr


Thickness of plates 6 mm X 10 mtr long, 10 mm X 12 mtr, 12 mm X 12 mtr & 70 mm X 10 mtr & once in a month 100 mm: 6 Mtr or 8 Mtr long.
Battery back up for selected magnet
Also need to understand how we can check the magnet is weak / capacity is lower down after some use? ? ?