The M-5329 Three-Phase LTC Backup Control provides extra protection

to save your customers from the hazards and inconvenience of excessively

high or low voltage on any phase. Defective LTC tapchanger controls can

cause either too high or too low a voltage along the line.

This can possibly damage customers’ motors, computers, or televisions.

Even when the control is operating properly, customers close to the

transformer may receive dangerously high voltage as the line drop compensator

attempts to maintain a constant voltage under heavy load at a central point on

the distribution line. The Beckwith Electric M-5329 LTC Backup Control can be

installed as a solution to both of these problems. It will prevent a defective LTC

tapchanger control from running the voltage outside the upper and lower voltage

limits and will prevent the line drop compensator from raising the voltage too

high under full load or overload conditions.

• Set the voltage bands on the M-5329 slightly wider than the transformer control

limits to ensure that a failed control will not result in a runaway LTC transformer.

• Under full or overload conditions, the M-5329 automatically takes over as an upper

voltage limit control that is not affected by load current, to prevent damage to

equipment close to the transformer.

• While the Block Raise contact prevents a raise operation, a Lower contact forces

the tapchanger down if the primary voltage subsequently rises.Capabilities of the

M-5329 include:

• Provides all components that must be added to an LTC Transformer for paralleling,

using the circulating current method.

• Prevents a defective LTC tapchanger control from running the voltage outside the

upper or lower limits.

• Prevents the line drop compensator from raising the voltage too high under full or

overload conditions.

• Monitors all three-phases and blocks LTC tapchanger operation if any phase is

outside the setpoints.Additionally, the M-5329 is fully transient protected and operates

within ±1% voltage accuracy over a temperature range of -40° to +80° C.