YASKAWA Sigma II Instruction Manual

TECHNICAL NOTE
MOTION PRODUCT ENGINEERING GROUP
Yaskawa Electric America - 2121 Norman Drive South – Waukegan IL 60085
(800) YASKAWA - Fax [phone]
3/6/2002 1 of 3 eng/02.005/MCD
Subject: Absolute Encoder Battery Options
Product: Sigma II
Battery Connection Options
In all, there are three options for connecting a backup battery for an absolute encoder. Only one
of these options needs to be used to back-up the absolute encoder. Yaskawa does not
recommend connection of multiple batteries to the absolute encoder circuit.
• Apply a battery (YEA part JZSP-BA01)
through connector CN8. A compartment to
hold this battery is built-in to the SGDH
amplifier (see figure below). This is the
most common option and allows for the
easiest replacement of a depleted battery.
• Apply a battery (see specifications below)
through the CN1 connector (pins 21 & 22).
• The final method is the battery backup
cable as described in this document. The
battery backup cable is the best option in
situations where the encoder cable is
disconnected often during machine
maintenance. The backup cable will
eliminate the need to re-initialize the
encoder after encoder cable
disconnection.
Battery Specifications
The backup battery specified for Sigma II motors with absolute encoders is Toshiba ER3V* or
equivalent. This battery is a thionyl chloride lithium battery rated at 3.6V with a life of 1000mAh.
The Yaskawa part number for the battery (with Yaskawa-added leads and connector) is
JZSP-BA01. This is the battery that is designed to be installed in the battery compartment of
SGDH amplifier.
If it is preferred to connect the absolute encoder battery through the CN1 connector, the
recommended battery is Toshiba ER6VC3*, rated at 3.6V and 2000mAh. The Yaskawa
equivalent battery is BA000518. It is not necessary to install batteries at both the host controller
and the SGDH amplifier.
Summary: The Sigma II absolute encoder requires a battery to backup the multi-turn data. There
are various ways of connecting the battery to the circuit that should be considered.
Battery
Com
p
artment
Battery Connector
(
CN8
)
Battery Connector
(
CN8
)
Battery
Com
p
artment
SGDH
30W to 5kW
SGDH
6kW and up
*Specifications for Toshiba ER3V and ER6V batteries are available at http://www.tbcl.co.jp/tb_e/ult_a_el.htm.

TECHNICAL NOTE
MOTION PRODUCT ENGINEERING GROUP
Yaskawa Electric America - 2121 Norman Drive South – Waukegan IL 60085
(800) YASKAWA - Fax [phone]
3/6/2002 2 of 3 eng/02.005/MCD
Alternate Battery Source
An alternate source for batteries is Tadiran Battery (www.tadiranbat.com), available through
electronic distributors such as Newark. Like the Toshiba batteries used in Yaskawa JZSP-BA01,
the Tadiran batteries are "thionyl chloride lithium" batteries, available in a 1/2-AA size that is
3.6V, 1000mAh (like the SGDH abs. enc. battery JZSP-BA01) and a AA size that is 3.6V,
2000mAh (like MP940 battery BA000518). Note: Tadiran batteries do not come with the pre-
wired leads and connectors for conveniently attaching to Yaskawa equipment like the Yaskawa
JZSP-BA01 and BA000518.
Battery Life
The serial encoder used in the Sigma II motor typically draws about 20 µA of current when the
power to the SGDH amplifier is turned off. In this condition, the maximum life of the standard
encoder data backup battery (P/N JZSP-BA01) is:
1000x10-3 A-hour / 20x10-6A = 50,000 hours (5.7 years)
When power is applied to the SGDH amplifier, the current draw from the battery is typically 3 µA.
Assuming that the SGDH amplifier is on for 12 hours and off for 12 hours each day, the maximum
life of the battery in this condition is:
3x10-6A x 12 hour=0.036mAh 20x10-6A x12 hour=0.24mAh
0.036 mAh + 0.24 mAh = 0.276mAh per day
1000mAh / 0.276mAh per day = 3623.2 days (9.9 years)
Battery Alarm
If the voltage of the battery for an absolute encoder drops to approx. 2.7V, the SGDH will
generate an Absolute Encoder Battery (A.83) Alarm. This alarm occurs when the SGDH receives
a signal from the absolute encoder when the power to the
SGDH is turned on. Therefore, the SGDH will not display the
alarm when the battery voltage drops below 2.7V while power
is being supplied to the SGDH. Follow the procedure outlined
below when replacing the battery:
1. Replace the battery while the control power to the
SGDH is ON.
2. After battery replacement, turn OFF the power to the
SGDH to clear the A.83 Absolute Encoder Battery
Alarm.
3. Turn ON the power to the SGDH and confirm that it
operates properly.

TECHNICAL NOTE
MOTION PRODUCT ENGINEERING GROUP
Yaskawa Electric America - 2121 Norman Drive South – Waukegan IL 60085
(800) YASKAWA - Fax [phone]
3/6/2002 3 of 3 eng/02.005/MCD
Constructing a Battery Backup Cable
Because the Sigma II absolute encoder does not have a high-storage capacitor as in the Sigma I,
multi-turn position data will be lost within a few seconds once the encoder cable is disconnected.
Normally, the encoder cable is not disconnected, and the data will be retained by the backup
battery installed in the amplifier. In some cases, it may be necessary to disconnect the encoder
cable, and the system must be able to backup the data in the absolute encoder. In these cases,
it is recommended to use a battery backup cable.
If machine maintenance requires frequent disconnection of the encoder cable, it is recommended
that a battery backup cable be built. This cable is installed at the motor upon machine
commissioning. With this backup cable in place, the encoder cable can be safely detected
without losing absolute encoder position. To construct this cable, place an absolute encoder
battery so that it is connected to the BAT+ and BAT- connections of the encoder (consult Sigma II
User’s Manual for wiring diagrams). A blocking diode should be added to the backup cable (see
diagram below).