  We derive a partial electric-magnetic (PEM) duality transformation of the
twisted quantum double (TQD) model TQD$(G,\alpha)$---discrete Dijkgraaf-Witten
model---with a finite gauge group $G$, which has an Abelian normal subgroup
$N$, and a three-cocycle $\alpha \in H^3(G,U(1))$. Any equivalence between two
TQD models, say, TQD$(G,\alpha)$ and TQD$(G',\alpha')$, can be realized as a
PEM duality transformation, which exchanges the $N$-charges and $N$-fluxes
only. Via the PEM duality, we construct an explicit isomorphism between the
corresponding TQD algebras $D^\alpha(G)$ and $D^{\alpha'}(G')$ and derive the
map between the anyons of one model and those of the other.
