diff --git a/andes/models/distributed/pvd1.py b/andes/models/distributed/pvd1.py
index 649caa4ef..788389882 100644
--- a/andes/models/distributed/pvd1.py
+++ b/andes/models/distributed/pvd1.py
@@ -324,7 +324,7 @@ def __init__(self, system, config):
                           unit='Hz', tex_name='f_{dev}',
                           )
 
-        self.DB = DeadBand1(u=self.Fdev, center=0.0, lower=self.fdbd, upper=0.0, gain=self.ddn,
+        self.DB = DeadBand1(u=self.Fdev, center=0.0, lower=self.fdbd, upper=999.0, gain=self.ddn,
                             info='frequency deviation deadband with gain',
                             )  # outputs   `Pdrp`
         self.DB.db.no_warn = True