MA7200 PLUS Operating Manual
TECO – Westinghouse Motor Company Sn-20 - Sn-23 Parameter Details
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Sn-19
Zero Speed Braking Selection (0 – 1)
When the run-source and frequency command is input from control circuit settings Sn-04=1 and Sn-05=1, If Sn-19 is
enabled, the holding torque will be generated in DC-braking mode when the frequency command is 0V and forward–run
source is on.
A time-chart for the above action is shown in Fig. 9.2.26 below. The zero-braking selection Sn-19 is set to 1 and the
DC-braking current Cn-15 is limited to within 20% of rated current.
Fig. 9.2.3.8 Zero Speed Braking Operation
Sn-20
External Fault Contact Selection (0 – 1)
Sn-20= 0: Input signal is from a normally open contact.
1: Input signal is from a normal closed contact.
Sn-21
External Fault Contact Detection Selection (0 – 1)
Sn-21= 0: Always detect.
1:Detect only during running.
Sn-22
Detection Mode Selection of External Fault (0 – 3)
When an external fault is detected, the following operation will be performed based on the setting of Sn-22.
Sn-22= 0: Decelerate to stop with the specified deceleration time of Bn-02.
1: Coast to stop.
2: Decelerate to stop with the specified deceleration time Bn-04.
3: Continue running.
Sn-23
Motor Overload Protection Selection (0 – 4)
Sn-23 = 0: Electronic overload protection disabled.
When Sn-23=1- 4, the electronic overload protection is enabled. The electronic thermal overload is detected
in accordance with the characteristic curves of operating time. vs. motor rated current setting (Cn-09).
Sn-23=1: The overload is detected according to the standard motor cold start curve.
2: The overload is detected according to the standard motor hot start curve.
3: The overload is detected according to the specific motor cold start curve.
4: The overload is detected according to the specific motor hot start curve.
Set Sn-23=0 (Disable) when 2 or more motors are connected to a single inverter. An alternate method can be
used to provide overload protection separately to each motor, such as connecting a thermal overload relay to
the power line of each motor.
The motor overload protection function should be set to Sn-23 = (2 or 4) (hot start
protection characteristic
curve) when the power supply is turned on and off frequently since the thermal values are reset each time the
power is turned off.
For a motor without a forced cooling fan, the heat dissipation capability is lower at low speed operation. In this
case the setting for Sn-23 can be either (1 or 2).
For a motor with a forced cooling fan, the heat dissipation capability is not dependent upon the rotating speed
Therefore, the setting Sn-23 can be either (3 or 4).
To protect the motor from overload by the use of electronic overload protection, ensure that the parameter
Cn-09 is set the rated current value shown on the motor nameplate.
See Fig. 9.2.3.9.
Cont.