Can Partners' remuneration be less than Book Profit calculation as per sec 40(b)

Yes

No restrictions

The amount of Remuneration paid to all the partners in aggregate shall not exceed the following amounts :

Book Profits :

1). On the first Rs. 3,00,000 of the Book Profits = Rs. 1,50,000 or 90% of the book profit whichever is "higher".

The above limits are the Maximum Amount of Remuneration paid to Working Partners in order to claim deduction under P&L. Note that the Act does not specifies any minimum limit. There is no such restrictions.

2). And On Balance Amount of Book Profit = 60%.

If Loss in Partnership Firms, maximum salary Rs. 1,50,000 allowed to Partners

Yes If the Firm incurs Loss , then Maximum deduction allowable is Rs. 1,50,000 i.e. Amount actually payable to working partners or Rs. 1,50,000 whichever is lower.

If loss otherwise the above way calculation as per shivam
you can't take any randomly figure

Thanks to all who responded to my query. 
@ Ayusmita - The reason for taking a random figure is because the Net profit % on Turnover was getting affected. I need to maintain 6% and above. 
The Partners Remuneration figure is arrived at by Deducting all expenses, Partners Interest, 6% Net Profit from the Total Turnover. Usually it is done as per sec 40(b). 

Please correct me if I am doing it wrong. 

You can take any amount for salary to partners but not excess of as per section 40 (b) or less any amount taken even random fiqure

As per section 40(b) the remuneration is always calculate by that you cannot change the figure
nor if you have loss
make adjustments in other calculation

@ ayusmita
If presumptive profit u/s 44AD is NOT OPTED.
Can the net profit be less than 6%*
My turnover is less than 10lac. Will tax audit be applicable if net profit is less than 6%
Books of Accounts maintained(only in Tally) 

The reason to decrease the Partners Remuneration was to accommodate 6% Net Profit even though 44AD was not opted. If Partners Remuneration is calculated as per Book Profits u/s 40(b) the net profit will be 3% (less than 6%)
*(6% for bank transactions)