某三相电源的电动势分别为eA=20sin(314t+16°)V eB=20sin(314t-104°) eC=20sin(314t+136°)V 当t=1

某三相电源的电动势分别为eA=20sin(314t+16°)V，eB=20sin(314t-104°)，eC=20sin(314t+136°)V，当t=13s时，该三相电动势之和是（）V。