CREATE TABLE table_24837750_1 (turbine_manufacturer VARCHAR, installed_capacity__mw_ VARCHAR)

How many turbine manufacturers installed a capacity of 189 MW?
SELECT COUNT(turbine_manufacturer) FROM table_24837750_1 WHERE installed_capacity__mw_ = "189"
SELECT COUNT("turbine_manufacturer") FROM "table_24837750_1" WHERE "189" = "installed_capacity__mw_"