Abrir Nueva Ventana en PyQt5 (ventana secundaria)

ventana_principal.py

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'ventana_principal.ui'
#
# Created by: PyQt5 UI code generator 5.10.1
#
# WARNING! All changes made in this file will be lost!

from PyQt5 import QtCore, QtGui, QtWidgets
from ventana_secundaria import Ui_ventana_secundaria

class Ui_ventana_principal(object):
    
    def abrir_ventana(self):
        self.window = QtWidgets.QMainWindow()
        self.ui = Ui_ventana_secundaria()
        self.ui.setupUi(self.window)
        ventana_principal.hide()
        self.window.show()
        
    def setupUi(self, ventana_principal):
        ventana_principal.setObjectName("ventana_principal")
        ventana_principal.resize(371, 297)
        self.centralwidget = QtWidgets.QWidget(ventana_principal)
        self.centralwidget.setObjectName("centralwidget")
        self.boton_abrir = QtWidgets.QPushButton(self.centralwidget)
        self.boton_abrir.setGeometry(QtCore.QRect(110, 140, 141, 51))
        self.boton_abrir.setObjectName("boton_abrir")
        
        self.boton_abrir.clicked.connect(self.abrir_ventana)
        

        self.etiqueta = QtWidgets.QLabel(self.centralwidget)
        self.etiqueta.setGeometry(QtCore.QRect(40, 40, 291, 41))
        font = QtGui.QFont()
        font.setPointSize(16)
        self.etiqueta.setFont(font)
        self.etiqueta.setObjectName("etiqueta")
        ventana_principal.setCentralWidget(self.centralwidget)
        self.barra_de_estado = QtWidgets.QStatusBar(ventana_principal)
        self.barra_de_estado.setObjectName("barra_de_estado")
        ventana_principal.setStatusBar(self.barra_de_estado)

        self.retranslateUi(ventana_principal)
        QtCore.QMetaObject.connectSlotsByName(ventana_principal)

    def retranslateUi(self, ventana_principal):
        _translate = QtCore.QCoreApplication.translate
        ventana_principal.setWindowTitle(_translate("ventana_principal", "Ventana Principal"))
        self.boton_abrir.setText(_translate("ventana_principal", "Abrir Ventana"))
        self.etiqueta.setText(_translate("ventana_principal", "Haga clic para abrir la ventana"))


if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    ventana_principal = QtWidgets.QMainWindow()
    ui = Ui_ventana_principal()
    ui.setupUi(ventana_principal)
    ventana_principal.show()
    sys.exit(app.exec_())

ventana_principal.ui

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>ventana_principal</class>
 <widget class="QMainWindow" name="ventana_principal">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>371</width>
    <height>297</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>Ventana Principal</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <widget class="QPushButton" name="boton_abrir">
    <property name="geometry">
     <rect>
      <x>110</x>
      <y>140</y>
      <width>141</width>
      <height>51</height>
     </rect>
    </property>
    <property name="text">
     <string>Abrir Ventana</string>
    </property>
   </widget>
   <widget class="QLabel" name="etiqueta">
    <property name="geometry">
     <rect>
      <x>40</x>
      <y>40</y>
      <width>291</width>
      <height>41</height>
     </rect>
    </property>
    <property name="font">
     <font>
      <pointsize>16</pointsize>
     </font>
    </property>
    <property name="text">
     <string>Haga clic para abrir la ventana</string>
    </property>
   </widget>
  </widget>
  <widget class="QStatusBar" name="barra_de_estado"/>
 </widget>
 <resources/>
 <connections/>
</ui>

ventana_secundaria.py

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'ventana_secundaria.ui'
#
# Created by: PyQt5 UI code generator 5.10.1
#
# WARNING! All changes made in this file will be lost!

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_ventana_secundaria(object):
    def setupUi(self, ventana_secundaria):
        ventana_secundaria.setObjectName("ventana_secundaria")
        ventana_secundaria.resize(568, 109)
        self.centralwidget = QtWidgets.QWidget(ventana_secundaria)
        self.centralwidget.setObjectName("centralwidget")
        self.etiqueta = QtWidgets.QLabel(self.centralwidget)
        self.etiqueta.setGeometry(QtCore.QRect(100, 20, 371, 41))
        font = QtGui.QFont()
        font.setPointSize(22)
        self.etiqueta.setFont(font)
        self.etiqueta.setObjectName("etiqueta")
        ventana_secundaria.setCentralWidget(self.centralwidget)
        self.statusbar = QtWidgets.QStatusBar(ventana_secundaria)
        self.statusbar.setObjectName("statusbar")
        ventana_secundaria.setStatusBar(self.statusbar)

        self.retranslateUi(ventana_secundaria)
        QtCore.QMetaObject.connectSlotsByName(ventana_secundaria)

    def retranslateUi(self, ventana_secundaria):
        _translate = QtCore.QCoreApplication.translate
        ventana_secundaria.setWindowTitle(_translate("ventana_secundaria", "Ventana Secundaria"))
        self.etiqueta.setText(_translate("ventana_secundaria", "Bienvenido a esta ventana"))


if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    ventana_secundaria = QtWidgets.QMainWindow()
    ui = Ui_ventana_secundaria()
    ui.setupUi(ventana_secundaria)
    ventana_secundaria.show()
    sys.exit(app.exec_())

ventana_secundaria.ui

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>ventana_secundaria</class>
 <widget class="QMainWindow" name="ventana_secundaria">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>568</width>
    <height>109</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>Ventana Secundaria</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <widget class="QLabel" name="etiqueta">
    <property name="geometry">
     <rect>
      <x>100</x>
      <y>20</y>
      <width>371</width>
      <height>41</height>
     </rect>
    </property>
    <property name="font">
     <font>
      <pointsize>22</pointsize>
     </font>
    </property>
    <property name="text">
     <string>Bienvenido a esta ventana</string>
    </property>
   </widget>
  </widget>
  <widget class="QStatusBar" name="statusbar"/>
 </widget>
 <resources/>
 <connections/>
</ui>