def __init__(self, name, host='127.0.0.1', port=27017):
        self.name = name
        self.host = host
        self.port = port
def winding_current(pos, current, ax=0):
    """plot winding currents"""
    if ax == 0:
        ax = plt.gca()
    ax.set_title('Winding Currents / A')
    ax.grid(True)
    for p, i in zip(pos, current):
        ax.plot(p, i)