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IRT Substation #21

By David M. Rosenthal

NYCT Substation 21 on Willow Place in Brooklyn Heights. This is a 1908 substation with seven rotary converters. Rotary converter #8 came from the Manhattan Elevated Railway and dates back to 1902. At the time the photographs were taken on October 22, 1996, rotary converters #2 and #8 (1902 Manhattan Elevated Railway) were placed on-line during the morning and evening rush hours to supplement the load from the adjacent solid state substations. The 1902 rotary converter was one of the two used at this time. Substation #21 is being converted to solid state now and a new local control panel was in place but not in-service when I was there in October of 1996. As of this writing in March 1999, all of the rotary converters at IRT Substation #21 are permanently out-of-service. All of the rotary converters will be removed and it is believed that one will be installed as a display piece for the New York Transit Museum. There are no other 25-cycle rotary converters still in service in the entire New York City Transit System. There are however two substations with 60 cycle rotary converters still in-service on the IND.

Thanks to my good friend Mr. Joe Cunningham for arranging access to IRT Substation #21 and special thanks to Mr. Michael Amoroso of New York City Transit and his Substation Operators for allowing me to photograph and video tape the substation. All photographs by David M. Rosenthal, October 22, 1996.

For more information on subway power generation visit:

What is a rotary converter?, a look at how rotary converter technology works and how it was used in the New York subway system, by Bernard S. Greenberg
The New York Subway: Its Construction and Equipment, which includes a 1904 description of the IRT subway's power house, power plant, and system of electrical supply.

(image 8312) (91k, 745x499) Country: United States City: New York System: New York City Transit Location: IRT Substation 21 Photo by: David M. Rosenthal Date: 10/22/1996 Notes: Rotary Converter #2 Viewed (this week/total): 20 / 15453	(image 8315) (121k, 742x504) Country: United States City: New York System: New York City Transit Location: IRT Substation 21 Photo by: David M. Rosenthal Date: 10/22/1996 Notes: DC brush arms and commutator for a rotary converter. Power from the brush arms feeds the third rail. Viewed (this week/total): 6 / 12983	(image 8316) (127k, 742x500) Country: United States City: New York System: New York City Transit Location: IRT Substation 21 Photo by: David M. Rosenthal Date: 10/22/1996 Notes: Switchboard gallery showing AC Switchgear console Viewed (this week/total): 4 / 13451	(image 8313) (105k, 739x502) Country: United States City: New York System: New York City Transit Location: IRT Substation 21 Photo by: David M. Rosenthal Date: 10/22/1996 Notes: General overview of Substation 21. Large rotary converter in background is from the Manhattan Elevated Railway of 1902. Viewed (this week/total): 8 / 13782
(image 8314) (106k, 499x737) Country: United States City: New York System: New York City Transit Location: IRT Substation 21 Photo by: David M. Rosenthal Date: 10/22/1996 Notes: AC brush arms and three phase commutators for a rotary converter. Power to these brush arms comes from three transformers. Viewed (this week/total): 9 / 11707	(image 8317) (87k, 737x498) Country: United States City: New York System: New York City Transit Location: IRT Substation 21 Photo by: David M. Rosenthal Date: 10/22/1996 Notes: Transformers feeding power to rotary converter #2. Each transformer is a single phase and steps-down 11000 VAC 25Hz to 390VAC. Viewed (this week/total): 1 / 8733	(image 8318) (95k, 491x749) Country: United States City: New York System: New York City Transit Location: IRT Substation 21 Photo by: David M. Rosenthal Date: 10/22/1996 Notes: AC switch gear console. Viewed (this week/total): 1 / 9483	(image 8319) (72k, 482x747) Country: United States City: New York System: New York City Transit Location: IRT Substation 21 Photo by: David M. Rosenthal Date: 10/22/1996 Notes: Sychroscope for synchronizing rotary converter. When a rotary converter is brought up to speed by the third rail, then the sychroscope and associated sychronizing lights are used to determine when rotary converter is in step or sychronized with the incoming AC power feeds. At that time, the rotary converter is disconnected from the third rail and the AC power feeders at connected to run the rotary converter. Viewed (this week/total): 3 / 9009
(image 8320) (101k, 496x744) Country: United States City: New York System: New York City Transit Location: IRT Substation 21 Photo by: David M. Rosenthal Date: 10/22/1996 Notes: Starting board for starting rotary convertors from a stop. Viewed (this week/total): 1 / 9629	(image 8321) (89k, 477x748) Country: United States City: New York System: New York City Transit Location: IRT Substation 21 Photo by: David M. Rosenthal Date: 10/22/1996 Notes: 11000 VAC Oil Circuit breakers. Viewed (this week/total): 1 / 9057	(image 8322) (127k, 492x745) Country: United States City: New York System: New York City Transit Location: IRT Substation 21 Photo by: David M. Rosenthal Date: 10/22/1996 Notes: Ground Detection Equipment for detecting ground on tunnel shields. Viewed (this week/total): 2 / 8427	(image 8323) (75k, 481x745) Country: United States City: New York System: New York City Transit Location: IRT Substation 21 Photo by: David M. Rosenthal Date: 10/22/1996 Notes: Basement ventilation tunnel for transformers. Viewed (this week/total): 2 / 8393
(image 8324) (90k, 493x748) Country: United States City: New York System: New York City Transit Location: IRT Substation 21 Photo by: David M. Rosenthal Date: 10/22/1996 Notes: DC switchgear to third rail. Viewed (this week/total): 4 / 10773