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IM00120

MSC-3 Instruction Manual

Dual Ramps

For applications that use a minimum speed, the MSC-3 provides a dual rate acceleration and

deceleration. The C033 DUAL RAMP option provides this feature. When enabled the rate of acceleration

and deceleration in the speed range 0 to B03 MOTOR Hz is at a rate of B03 MOTOR Hz/C032 S TIME.

The diagram below shows the reference as a function of time. Refer to C033 DUAL RAMP for details.

C010 MIN Hz

Speed

Time

Reference

Slope = B03 MOTOR Hz / C032 S TIME

Slope = B03 MOTOR Hz / C030 ACCEL TIME

Slope = B03 MOTOR Hz / C031 DECEL TIME

Key ramp conguration parameters are:

• C033 DUAL RAMP (function activation)

• C032 S TIME

• C030 ACCEL TIME

• C031 DECEL TIME

• B03 MOTOR Hz

Essential Services Override

There are circumstances in some applications for which it is desirable to disable certain of the protective

features of the MSC-3. These are situations where continued operation has a higher priority than

preventing damage to the MSC-3 or associated motor. A typical example is a building air conditioning

application in which a fan is required to operate as part of a smoke clearance system. Various standards,

for example, AS/NZS 1668.1:1998: The use of ventilation and air conditioning in buildings - Fire and

smoke control in multi-compartment buildings require that all thermal protection be disabled during

operation in a smoke clearance mode and equipment allowed, if necessary, to run to destruction. The

MSC-3 provides a special mode, Essential Services Override (ESO), to give effect to these requirements.

Operation in ESO requires a control terminal to be congured for the ESO function and that this terminal

to be connected to +5V (terminal 1) whenever ESO operation is required. During ESO operation the

MSC-3 is forced to run and the following protective functions are disabled:

• Heat sink over temperature protection

• I2t protection

• Motor thermistor protection (if tted)

• Supply Fail

In addition, the Auto Restart function is automatically enabled with unlimited auto restarts permitted.

In order to allow the MSC-3 to be independently optimised for both the usual operating condition and

operation in ESO mode, separate parameters are provided for ESO and non ESO operating modes.

Zener MSC-3 User Manual

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