Unless there is a specific bar under the contract, it is always open for the arbitrator / Arbitral Tribunal to award pendente lite interest

Arbitration and Conciliation Act, 1996; Section 31(7) - Unless there is a specific bar under the contract, it is always open for the arbitrator / Arbitral Tribunal to award pendente lite interest. (Para 7.5) 

Indian Railway Construction Company v. National Buildings Construction Corporation, 

2023 LiveLaw (SC) 210 : 2023 INSC 248 : (2023) 2 SCR 713