GE 151X1235FD01PK01   High-speed Digital Input Interface Board

151X1235FD01PK01   High-speed Digital Input Interface Board

Output Power

Due to the high fault current capacity of the generator, the static starter load inverter

output is connected to the starting bus through current limiting fuses. These fuses are

required to protect the power converter and interconnecting cables in the event of an

inverter fault during the starting operation.

7FA and 7FB turbine

applications do not require

the ac reactors while 9FA and

9H turbine applications do

require them.

Customer

Water

An ac reactor is sometimes connected between the current limiting fuses and the

starting bus in order to increase the commutating reactance for proper operation of

the inverter. The ac reactors are used when the phase-to-ground capacitance on the

ac or dc buses exceeds 0.125 mfd.

The output starting bus is connected to the generator stator by a motor operated

disconnect switch (89SS). The switch is rated based on generator terminal voltage

and Static Starter full load current. The switch is electrically interlocked with the

generator main breaker (52G) to prevent operation of the switch when the generator

is connected to the system bus.

Cooling System

The Static Starter power converter uses a liquid cooling system to transfer heat from

heat producing devices (such as SCRs and high wattage resistors) to a remote heat

exchanger. The cooling system is closed-loop with a covered reservoir for makeup

coolant. Coolant circulates from the pump discharge to the remote heat exchanger to

the power conversion bridges, and returns to the pump. A portion of the coolant

bypasses to a de-ionizer system to maintain the coolant resistivity. This cooling

system flow is shown in the following figure.

The coolant is a water/glycol mixture that prevents freezing with lower outside

ambient temperatures. The system should initially be charged with a mixture of

distilled, de-mineralized, or de-ionized water and pure glycol. Makeup coolant must

be a similar mixture to maintain the desired freeze protection. Although both

propylene and ethylene glycol are approved for use, propylene glycol is preferred

because of higher electrical resistance, longer de-ionizer life, and non-toxicity.

Redundant pumps circulate the coolant. The pressure switch and interlocking pump

motor starters provide automatic transfer to the back-up pump in the event of coolant

pressure loss. Isolation valves allow the pumps to be changed online without

draining the system.

A remote mounted liquid-to-liquid heat exchanger is used to remove heat from the

closed loop system. A remote mounted liquid-to-air heat exchanger may be supplied

as an option. The liquid-to-air heat exchanger includes redundant cooling blowers.

A coolant temperature switch and interlocking blower motor starters provide

automatic transfer to the back-up blower.

A temperature-regulating valve prevents the coolant temperature from falling below

a minimum of approximately 27°C (80 °F) by allowing some of the coolant to

bypass the heat exchanger.