power controller

9007pinza

Member
Joined
27 May 2011
Messages
16
Gents.
Often wonder how the power controller on the English Electric/Brush locomotives with Sulzer engines, 'worked'?
Were they electrical, electronics, hydraulic or pneumatic.?.
I presume they were linked to the engine govenor system, or ,were they linked to the generator, which in turn controlled the engine.
I can imaging they gave a lot of trouble !
 
Sponsor Post - registered members do not see these adverts; click here to register, or click here to log in
R

RailUK Forums

GC class B1

Member
Joined
19 Jun 2021
Messages
46
Location
East midlands
From memory the power controller operated the power unit governor electrically - by switch settings I think. The governor operated both the fuel rack and generator excitation. They were pretty simple in control terms and pretty reliable. The principle was that the power controller position was in effect a generator output power setting and the engine part of the governor controlled the fuel input to meet the generator power output required. If the generator load slowed the engine speed then more fuel would be injected and if the engine speeded up less fuel would be injected. This is a simple explanation that I think is correct in principle but others may correct me If I am mistake.

I don’t recall any Sulzer engined locos with English Electric traction equipment. EE locos had EE engines. Later class 20 had an early electronic control system. I think these were designated KV5 and the later improved KV10. I don’t have any experience of other EE locos.

Thank you to Hexagon789 for providing a correct explanation below I think I was mixing up Brish/Sulzer and EE governors.
 
Last edited:

hexagon789

Veteran Member
Joined
2 Sep 2016
Messages
11,779
Location
Glasgow
Gents.
Often wonder how the power controller on the English Electric/Brush locomotives with Sulzer engines, 'worked'?
Were they electrical, electronics, hydraulic or pneumatic.?.
I presume they were linked to the engine govenor system, or ,were they linked to the generator, which in turn controlled the engine.
I can imaging they gave a lot of trouble !
Diesels such as the Sulzers and English Electrics had all-speed governors on the engines, so there were no fixed notches as such on the controllers. For Class 47s, the power controller itself operates a regulating air valve which fed air to a cylinder in the governor, this then operated the fuel racks on the engine via linkages.

An oil vane motor in the governor also controlled a potential divider on earlier locos or a linear voltage differentiating transducer (LVDT) on those converted to ETH, to vary the excitation current in the main generator. This enables the output from the generator to match the load the engine was capable of delivering for the regulating air being fed from the power controller. The Brush/Sulzer system was well designed and it was almost impossible to overload the engine.

As regards what happens when the power controller is moved, when the power controller is moved to the "ON" position, this feeds about 5psi of air pressure to the governor. It doesn't increase the engine speed, but enables the engine to supply enough torque to apply a small amount of tractive effort running at idle speed. With the controller open to a 1/4, the regulating air is around 13psi and the engine runs faster thus delivering a greater load. The oil vane motor will increase the output from the potential divider/LVDT and the excitation current will be increased and the main generator will then produce correspondingly more voltage and current for the traction motors. 30psi in the governor was somewhere between 1/2 and 3/4 power while 50 psi is full power.

(This is taken from a reference to how the Brush two-wire Class 47/7 push-pull system worked and I've tried to remove such references to simplify things, but apologies if I've missed any.)
 

Cowley

Established Member
Associate Staff
General Discussion
Railtours & Preservation
Modelling & Games
Joined
15 Apr 2016
Messages
11,035
Location
Devon
Diesels such as the Sulzers and English Electrics had all-speed governors on the engines, so there were no fixed notches as such on the controllers. For Class 47s, the power controller itself operates a regulating air valve which fed air to a cylinder in the governor, this then operated the fuel racks on the engine via linkages.

An oil vane motor in the governor also controlled a potential divider on earlier locos or a linear voltage differentiating transducer (LVDT) on those converted to ETH, to vary the excitation current in the main generator. This enables the output from the generator to match the load the engine was capable of delivering for the regulating air being fed from the power controller. The Brush/Sulzer system was well designed and it was almost impossible to overload the engine.

As regards what happens when the power controller is moved, when the power controller is moved to the "ON" position, this feeds about 5psi of air pressure to the governor. It doesn't increase the engine speed, but enables the engine to supply enough torque to apply a small amount of tractive effort running at idle speed. With the controller open to a 1/4, the regulating air is around 13psi and the engine runs faster thus delivering a greater load. The oil vane motor will increase the output from the potential divider/LVDT and the excitation current will be increased and the main generator will then produce correspondingly more voltage and current for the traction motors. 30psi in the governor was somewhere between 1/2 and 3/4 power while 50 psi is full power.

(This is taken from a reference to how the Brush two-wire Class 47/7 push-pull system worked and I've tried to remove such references to simplify things, but apologies if I've missed any.)

Really interesting thanks Hexagon.
 

9007pinza

Member
Joined
27 May 2011
Messages
16
Thanks gents, very interesting. I was used to trucks, with a direct mechanical linkage, (sometimes air), to the injection pump.
 

hexagon789

Veteran Member
Joined
2 Sep 2016
Messages
11,779
Location
Glasgow
Really interesting thanks Hexagon.
No worries, you may have read it before because it is exactly what I posted when referring to Class 47/7s in a thread sone years ago.

Thanks gents, very interesting. I was used to trucks, with a direct mechanical linkage, (sometimes air), to the injection pump.
Class 50s as built are a bit different. They had a 'constant current control system, thus instead of the power handle controlling power output through a 'closed-loop' control system consisting of the engine governor and load regulator the 50's power handles controlled both power output and traction motor current with a further separate Current Limiting Control allowing a restricted maximum motor current to be set by the driver.

The unique control system would require in-depth explanation to fully explain the differences and advantages over more conventional control.
 

Pigeon

Member
Joined
8 Apr 2015
Messages
423
You wouldn't think of not doing it now, but it was a lot more difficult before you could do it all electronically. Always raised my eyebrows a bit the way keeping the traction motors from overheating was so dependent in those days on having the driver in the feedback loop - driving on the ammeter up long banks and so on. (There is an excellent scene of the driver doing this in one of the Woodhead electrics in an old black and white cine film which is now on youtube somewhere. Amazingly fine control available too - how many notches?)
 

hexagon789

Veteran Member
Joined
2 Sep 2016
Messages
11,779
Location
Glasgow
You wouldn't think of not doing it now, but it was a lot more difficult before you could do it all electronically. Always raised my eyebrows a bit the way keeping the traction motors from overheating was so dependent in those days on having the driver in the feedback loop - driving on the ammeter up long banks and so on. (There is an excellent scene of the driver doing this in one of the Woodhead electrics in an old black and white cine film which is now on youtube somewhere. Amazingly fine control available too - how many notches?)
Testing my memory, but I think it was 15 resistance notches in both series and parallel and then four(?) stages of field weakening. So that would make 38 effective notches.

Edit: Yes, I've confirmed that now - 19 notches in series and in parallel which break down into 15 resistance notches then four 'field weakening' notches for a grand total of 38 power settings.
 

Top