Rescue workers have used a cherry picker to evacuate dozens of passengers from Sydney's monorail after an electrical fault brought the system to a standstill above Paddy's Market.

Carriages were still stuck near Paddy's Market and at Darling Drive in Ultimo on Monday evening, but about 80 people have now been rescued.

Firefighters used a crane to evacuate the stranded passengers.

Fire and Rescue officers used cranes and ladders to get the passengers to the ground.

Some passengers were checked for dehydration and anxiety but there were no reports of any serious injuries.

Paramedic Jason Mattser says it was around 40 degrees Celsius inside with the doors shut and some passengers had to be treated for heat exposure and dehydration.

Molly Trounson, 14, was holidaying from Melbourne and says while she remained calm, others on board were very upset.

"We were just wondering what's happening and then the guards crawled through and told us there was a power outage," she said.

"We were in there for about three hours and it got really hot and there were little kids there and they started panicking and their grandma was panicking.

"Then everyone was panicking and people were crying."

'Extremely hot'

Lorretta Inverardi from Queensland says the incident was handled well.

"The conductors on board were fantastic, going through the carriages to let us know where things are at which was out of their control," she said.

But Ms Inverardi says there was a lot of anxiety among passengers.

"Because people were missing their flights and it was extremely hot in there. We spent two hours in there. It wasn't pleasant," she said.

It was an experience Nina Elhami- Manesh will not forget in a hurry.

"We were getting nervous and claustrophobic in a way but [now] we're down in the ground and I don't know if I want to go in that for a while," she said.

Ausgrid has issued a statement saying power has now been safely restored to the monorail.

The electricity provider says a fault on an underground cable caused the outage shortly before 2:00pm AEST on Monday, and power was restored about 4:45pm.

It says around 100 customers in Pyrmont and Darling Harbour were affected.

Earlier this year the New South Wales Government announced the monorail would be scrapped.