def copyVoltageKeywords(inhdr, outhdr, detector):
    """Copy keywords for high voltages from one header to another.

    This is for copying the high voltage keywords from the input extension
    header to the primary header of the csum file.

    Parameters
    ----------
    inhdr: pyfits Header object
        Input header.

    outhdr: pyfits Header object
        Output header.

    detector: {"FUV", "NUV"}
        Detector name.
    """
    if detector == 'FUV':
        outhdr['dethvla'] = inhdr.get('dethvla', -999.0)
        outhdr['dethvlb'] = inhdr.get('dethvlb', -999.0)
        outhdr['dethvca'] = inhdr.get('dethvca', -999.0)
        outhdr['dethvcb'] = inhdr.get('dethvcb', -999.0)
        outhdr['dethvna'] = inhdr.get('dethvna', -999.0)
        outhdr['dethvnb'] = inhdr.get('dethvnb', -999.0)
    elif detector == 'NUV':
        outhdr['dethvl'] = inhdr.get('dethvl', -999.0)
        outhdr['dethvc'] = inhdr.get('dethvc', -999.0)
