High DC Current Measurement

Standard clamp meters only measure AC current. You need either a clamp meter designed for DC current or a current shunt.

The following is a suitable example 2000A AC/DC clamp meter

http://www.extech.com/instruments/product.asp?catid=26&prodid=90

also google "dc current clamp meter" for plenty more.

A current shunt at 1450A DC is going to be expensive but is a possibility.

http://en.wikipedia.org/wiki/Shunt_(electrical)

I would go with a suitable DC clamp meter for your application unless you cannot physically get the clamp head around the motor wiring or bus-work anywhere (even then you should be able to find a DC clamp meter with extra-wide jaws).

All DC motor used DC speed drives to control the motor. In your speed drive unit it is already design the output for the DC current to be connect to the DC current indicator for the display of the DC current.

There is AC/DC tong tester available in the market and you can use it to check our DC current of your DC Motor. It not expensive.