Toshiba H9 operation manual F304 F305, Overvoltage Limit Operation

F304 F305

Dynamic Braking

Program ⇒ Protection ⇒ Dynamic Braking

This parameter Enables/Disables the Dynamic Braking system.

Settings:

0 — Off

1 — On with Overload Detection

2 — On without Overload Detection

Dynamic Braking uses the transistor IGBT7 to dissipate the bus voltage when required.

IGBT7 is a standard item on the 25 HP and below H9 ASD 230-volt systems and is standard on the 400 HP and below for the for the 460-volt systems. IGBT7 is optional for all remaining systems.

Direct Access Number — F304

Parameter Type — Selection List

Factory Default — Off

Changeable During Run — No

Dynamic Braking

Dynamic Braking is used to prevent over-voltage faults during rapid deceleration or constant speed run on cyclic overhauling applications.

Dynamic Braking dissipates regenerated energy in the form of heat. When using a DBR use thermal protection.

The resistive load is connected across terminals PA and PB (non-polarized). Using a low-value, high-wattage resistance as a load for the generated current, the resistive load dissipates the induced energy.

Dynamic Braking helps to slow the load quickly; it cannot act as a holding brake.

The Dynamic Braking function may be setup and enabled by connecting a braking resistor from terminal PA to PB of the drive and providing the proper information at F304, F308, and F309.

See the section titled Dynamic Braking Resistor Wire/Cable Specifications on pg. 268 for more information on using the DBR system and for assistance in selecting the appropriate resistor for a given application.

Overvoltage Limit Operation	Direct Access Number — F305
Program ⇒ Protection ⇒ Stall	Parameter Type — Selection List
This parameter enables the Overvoltage Limit function. This feature is used to	Factory Default — (ASD-dependent)
set the upper DC bus voltage threshold that, once exceeded, will cause an	Changeable During Run — Yes
Overvoltage Stall.
An Overvoltage Stall increases the output frequency of the drive during
deceleration for a specified time in an attempt to prevent an Overvoltage Trip.
If the overvoltage threshold level setting of parameter F626 is exceeded for
over 4 mS, an Overvoltage Trip will be incurred.

Note: This parameter setting may increase deceleration times.

Settings:

0 — Enabled (Overvoltage Stall)

1 — Disabled

2 — Enabled (Forced Shorted Deceleration)

3 — Enabled (Forced Dynamic Braking Deceleration)

136 H9 ASD Installation and Operation Manual